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1

Gallium alloy films investigated for use as boundary lubricants  

NASA Technical Reports Server (NTRS)

Gallium alloyed with other low melting point metals has excellent lubricant properties of fluidity and low vapor pressure for high temperature or vacuum environments. The addition of other soft metals reduces the corrosivity and formation of undesirable alloys normally found with gallium.

1966-01-01

2

Method for Plutonium-Gallium Separation by Anodic Dissolution of a Solid Plutonium-Gallium Alloy  

SciTech Connect

Purified plutonium and gallium are efficiently recovered from a solid plutonium-gallium (Pu-Ga) alloy by using an electrorefining process. The solid Pu-Ga alloy is the cell anode, preferably placed in a moving basket within the electrolyte. As the surface of the Pu-Ga anode is depleted in plutonium by the electrotransport of the plutonium to a cathode, the temperature of the electrolyte is sufficient to liquify the surface, preferably at about 500 C, resulting in a liquid anode layer substantially comprised of gallium. The gallium drips from the liquified surface and is collected below the anode within the electrochemical cell. The transported plutonium is collected on the cathode surface and is recovered.

Miller, William E.; Tomczuk, Zygmunt

1998-12-08

3

Microfluidic platforms for gallium-based liquid metal alloy  

NASA Astrophysics Data System (ADS)

As an alternative to toxic mercury, non-toxic gallium-based liquid metal alloy has been gaining popularity due to its higher thermal and electrical conductivities, and low toxicity along with liquid property. However, it is difficult to handle as the alloy becomes readily oxidized in atmospheric air environment. This instant oxidation causes the gallium-based liquid metal alloy to wet almost any solid surface. Therefore, it has been primarily limited to applications which rely only on its deformability, not on its mobility. In this research, various approaches to mobilize gallium-based liquid metal alloy were investigated. Multi-scale surface patterned with polydimethylsiloxane (PDMS) micro pillar array showed super-lyophobic property against gallium-based liquid metal alloy by minimizing the contact area between the solid surface and the liquid metal, and it was expanded to a three-dimensional tunnel shaped microfluidic channel. Vertically-aligned carbon nanotube forest leads to another promising super-lyophobic surface due to its hierarchical micro/nano scale combined structures and chemical inertness. When the carbon nanotubes were transferred onto flexible PDMS by imprinting, the super-lyophobic property was still maintained even under the mechanical deformation such as stretching and bending. Alternatively, the gallium-based liquid metal can be manipulated by modifying the surface of liquid metal itself. With chemical reaction with HCl 'vapor', the oxidized surface (mainly Ga2O3/Ga2O) of gallium-based liquid metal was converted to GaCl3/InCl 3 resulting in the recovery of non-wetting characteristics. Paper which is intrinsically porous is attractive as a super-lyophobic surface and it was found that hydrochloric acid (HCl) impregnation enhanced the anti-wetting property by the chemical reaction. As another alternative method, by coating the viscoelastic oxidized surface of liquid metal with ferromagnetic materials (CoNiMnP or Fe), it showed non-wetting property and became moveable by applying a magnetic field. Finally, using its metallic and liquid properties, microfluidic-based applications of gallium-based liquid metal alloy such as inkjet printing and reconfigurable photomask were investigated. A clog-free and oxide-free inkjet printing technique was developed by incorporating HCl-impregnated paper as orifice. Inkjet-printed liquid metal line can be used as a metallic interconnect even with significant deformation of the flexible substrate. Additionally, based on its ultraviolet light blocking property, a reconfigurable photolithography using gallium-based liquid metal alloy was demonstrated in a PDMS-based 7-segments microfluidic channel by showing single digit numbers ('0'˜'9') with attainable minimum feature size of 10 microm.

Kim, Daeyoung

4

A suggested method for mixing direct filling restorative gallium alloy.  

PubMed

Good wettability is one of the desirable physical properties of mercury-free gallium-based alloys (Gallium Alloy GF). However, wettability, while providing good adhesion to the cavity wall, has the adverse effect of causing stickiness to the inside of the capsule during mixing, and also to the metal hand instruments used for packing. To control this stickiness the alloy mixture was treated with a small amount of alcohol using two different methods. In both groups (alcohol-added and alcohol-treated groups), 5, 10, or 15 microliters of alcohol was added. However, for the alcohol-treated group, the alcohol was shaken from the mixture. In both groups, remarkable improvement was seen in their handling properties, for the alloy mixture did not adhere to the inside of the capsule and was easily taken out as one mass. Compressive strength, tensile strength, and creep were tested in the alcohol-added/-treated groups, and compared with those of a control (conventionally mixed gallium alloy) and a high-copper amalgam (Spherical-D). All tests were done according to ISO 1559 (International Organization for Standardization, 1986), and the results were analyzed using one-way ANOVA (Duncan, P < 0.05). Surface microhardness (KHN) and dimensional change during hardening were evaluated according to ISO 1559 and compared to the control results. In mixing Gallium Alloy GF, an addition of less than 5 microliters of alcohol had the effect of preventing the alloy mixture from sticking to the inside of the capsule and remarkably enhanced the handling properties. This suggested mixing technique did not alter either the mechanical properties tested for this material or the desirable dimensional expansion that occurs during hardening. PMID:8957910

Momoi, Y; Asami, Y; Ozawa, M; Kohno, A

1996-01-01

5

The microstructural, mechanical, and fracture properties of austenitic stainless steel alloyed with gallium  

Microsoft Academic Search

The mechanical and fracture properties of austenitic stainless steels (SSs) alloyed with gallium require assessment in order to determine the likelihood of premature storage-container failure following Ga uptake. AISI 304 L SS was cast with 1, 3, 6, 9, and 12 wt pct Ga. Increased Ga concentration promoted duplex microstructure formation with the ferritic phase having a nearly identical composition

D. G. Kolman; J. F. Bingert; R. D. Field

2004-01-01

6

Temperature dependencies of elasticity characteristics for tellurium-alloyed gallium arsenide  

SciTech Connect

The influence of thermal loading on the elasticity characteristics of low-alloyed monocrystalline gallium arsenide has been studied by a precision ultrasonic method in the temperature range from 190 to 380 K. The deviation of the obtained temperature dependencies from some averaged curve is shown to be more appreciable in the first cycle of thermal loading than in subsequent ones.

Troyanskii, A.I.; Borisenko, V.A. (Academy of Sciences, Kiev (Ukraine). Institute for Problems of Strength)

1994-05-01

7

Temperature dependences of elastic characteristics of tellurium-alloyed gallium arsenide  

SciTech Connect

The influence of thermal loading on the elastic characteristics of weakly alloyed fine-crystalline gallium arsenide is studied by a precision ultrasonic method in the range 190-380 K. It is shown that the deviations of the obtained temperature dependences of the elastic characteristics from the average curve are more sensitive in the first thermocycling cycle.

Borisenko, V.A.; Troyanskii, A.I. [Institute of Strength Problems, Kiev (Ukraine)

1994-09-01

8

Galvanic corrosion and cytotoxic effects of amalgam and gallium alloys coupled to titanium.  

PubMed

The aim of this study was to examine and compare the galvanic corrosion of a conventional, a dispersed high-copper, and a palladium-enriched spherical high-copper amalgam and a gallium alloy coupled to titanium in saline and cell culture solutions, and to evaluate the effects of the couples on cultured cells. The potentials and charge transfers between amalgams and titanium were measured by electrochemical corrosion methods. Cytotoxicity of the couples, as indicated by the uptake of neutral red vital stain, was determined in 24-h direct contact human gingival fibroblast cell cultures. Results of this study indicated that before connecting the high-copper amalgams to titanium, the amalgams exhibited more positive potentials which resulted in initial negative charge transfers, i.e. corrosion of titanium. However, this initial corrosion appeared to cause titanium to passivate, and a shift in galvanic currents to positive charge transfers, i.e. corrosion of the amalgam samples. Lower galvanic currents were measured for the amalgam-titanium couples as compared to the gallium alloy-titanium couple. Coupling the conventional or the palladium-enriched high-copper amalgams to titanium did not significantly affect the uptake of neutral red as compared to cells not exposed to any test alloy. However, significant cytotoxic effects were observed when the dispersed-type high-copper amalgam and the gallium alloy were coupled to titanium. Even though the corrosion currents measured for these couples were less than gold alloys coupled to amalgam, these results suggest there is the potential for released galvanic corrosion products to become cytotoxic. These data warrant further investigations into the effects of coupling amalgam and gallium alloys to titanium in the oral environment. PMID:8831065

Bumgardner, J D; Johansson, B I

1996-06-01

9

The microstructural, mechanical, and fracture properties of austenitic stainless steel alloyed with gallium  

Microsoft Academic Search

The mechanical and fracture properties of austenitic stainless steels (SSs) alloyed with gallium require assessment in order\\u000a to determine the likelihood of premature storage-container failure following Ga uptake. AISI 304 L SS was cast with 1, 3,\\u000a 6, 9, and 12 wt pct Ga. Increased Ga concentration promoted duplex microstructure formation with the ferritic phase having\\u000a a nearly identical composition

D. G. Kolman; J. F. Bingert; R. D. Field

2004-01-01

10

Thermodynamic properties of lanthanum in gallium-indium eutectic based alloys  

NASA Astrophysics Data System (ADS)

Activity and activity coefficients of lanthanum were determined for the first time in gallium-indium eutectic based alloys in a wide temperature range employing electromotive force method. Activity of ?-La and super cooled liquid lanthanum in Ga-In eutectic based alloys between 573 and 1073 K linearly depends on the reciprocal temperature: lga=5.660-{15,352}/{T}±0.093 lga=6.074-{15,839}/{T}±0.093 Activity coefficients of ?-La and super cooled liquid lanthanum in this system at 617-1073 K are described by the following equations: lg?=3.786-{12,216}/{T}±0.171 lg?=4.199-{12,703}/{T}±0.171 In addition activity of lanthanum in alloys with In was also determined in the same temperature range.

Shchetinskiy, A. V.; Dedyukhin, A. S.; Volkovich, V. A.; Yamshchikov, L. F.; Maisheva, A. I.; Osipenko, A. G.; Kormilitsyn, M. V.

2013-04-01

11

Czochralski growth of gallium indium antimonide alloy crystals  

SciTech Connect

Attempts were made to grow alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb by the conventional Czochralski process. A transparent furnace was used, with hydrogen purging through the chamber during crystal growth. Single crystal seeds up to about 2 to 5 mole% InSb were grown from seeds of 1 to 2 mole% InSb, which were grown from essentially pure GaSb seeds of the [111] direction. Single crystals were grown with InSb rising from about 2 to 6 mole% at the seed ends to about 14 to 23 mole% InSb at the finish ends. A floating-crucible technique that had been effective in reducing segregation in doped crystals, was used to reduce segregation in Czochralski growth of alloy crystals of Ga{sub 1{minus}x}In{sub x}Sb. Crystals close to the targeted composition of 1 mole% InSb were grown. However, difficulties were encountered in reaching higher targeted InSb concentrations. Crystals about 2 mole% were grown when 4 mole% was targeted. It was observed that mixing occurred between the melts rendering the compositions of the melts; and, hence, the resultant crystal unpredictable. The higher density of the growth melt than that of the replenishing melt could have triggered thermosolutal convection to cause such mixing. It was also observed that the floating crucible stuck to the outer crucible when the liquidus temperature of the replenishing melt was significantly higher than that of the growth melt. The homogeneous Ga{sub 1{minus}x}In{sub x}Sb single crystals were grown successfully by a pressure-differential technique. By separating a quartz tube into an upper chamber for crystal growth and a lower chamber for replenishing. The melts were connected by a capillary tube to suppress mixing between them. A constant pressure differential was maintained between the chambers to keep the growth melt up in the growth chamber. The method was first tested with a low temperature alloy Bi{sub 1{minus}x}Sb{sub x}. Single crystals of Ga{sub 1{minus}x}In{sub x}Sb were grown with uniform compositions up to nearly 5 mole% InSb.

Tsaur, S.C.

1998-02-01

12

Measured iron-gallium alloy tensile properties under magnetic fields  

NASA Astrophysics Data System (ADS)

Tension testing is used to identify Galfenol material properties under low level DC magnetic bias fields. Dog bone shaped specimens of single crystal Fe100-xGax, where 17<=x<=33, underwent tensile testing along two crystalographic axis orientations, [110] and [100]. The material properties being investigated and calculated from measured quantities are: Young's modulus and Poisson's ratio. Data are presented that demonstrate the dependence of these material properties on applied magnetic field levels and provide a preliminary assessment of the trends in material properties for performance under varied operating conditions. The elastic properties of Fe-Ga alloys were observed to be increasingly anisotropic with rising Ga content for the stoichiometries examined. The largest elastic anisotropies were manifested in [110] Poisson's ratios of as low as -0.63 in one specimen. This negative Poisson's ratio creates a significant in-plane auxetic behavior that could be exploited in applications that capitalize on unique area effects produced under uniaxial loading.

Yoo, Jin-Hyeong; Flatau, Alison B.

2004-07-01

13

Alloying and Structure of Ultrathin Gallium Films on the (111) and (110) Surfaces of Palladium  

PubMed Central

Growth, thermal stability, and structure of ultrathin gallium films on Pd(111) and Pd(110) are investigated by low-energy ion scattering and low-energy electron diffraction. Common to both surface orientations are growth of disordered Ga films at coverages of a few monolayers (T = 150 K), onset of alloy formation at low temperatures (T ? 200 K), and formation of a metastable, mostly disordered 1:1 surface alloy at temperatures around 400–500 K. At higher temperatures a Ga surface fraction of ?0.3 is slightly stabilized on Pd(111), which we suggest to be related to the formation of Pd2Ga bulk-like films. While on Pd(110) only a Pd-up/Ga-down buckled surface was observed, an inversion of buckling was observed on Pd(111) upon heating. Similarities and differences to the related Zn/Pd system are discussed. PMID:24089625

2013-01-01

14

Further studies of the anodic dissolution in sodium chloride electrolyte of aluminium alloys containing tin and gallium  

Microsoft Academic Search

As part of a programme to develop a high power density, Al\\/air battery with a NaCl brine electrolyte, the high rate dissolution of an aluminium alloy containing tin and gallium was investigated in a small volume cell. The objective was to define the factors that limit aluminium dissolution in condition that mimic a high power density battery. In a cell

Maria Nestoridi; Derek Pletcher; Julian A. Wharton; Robert J. K. Wood

2009-01-01

15

Fabrication of magnetic nano liquid metal fluid through loading of Ni nanoparticles into gallium or its alloy  

NASA Astrophysics Data System (ADS)

In this study, Ni nanoparticles were loaded into the partially oxidized gallium and its alloys to fabricate desired magnetic nanofluid. It was disclosed that the Ni nanoparticles sharply increased the freezing temperature and latent heat of the obtained magnetic nano liquid metal fluid, while the melting process was less affected. For the gallium sample added with 10 vol% coated Ni particles, a hysteresis loop was observed and the magnetization intensity decreased with the increase of the temperature. The slope for the magnetization-temperature curve within 10-30 K was about 20 times of that from 40 K to 400 K. Further, the dynamic impact experiments of striking magnetic liquid metal droplets on the magnet revealed that the regurgitating of the leading edge of the liquid disk and the subsequent wave that often occurred in the gallium-indium droplets would disappear for the magnetic fluids case due to attraction force of the magnet.

Xiong, Mingfeng; Gao, Yunxia; Liu, Jing

2014-03-01

16

Effect of microtextured surface topography on the wetting behavior of eutectic gallium-indium alloys.  

PubMed

Liquid-embedded elastomer electronics have recently attracted much attention as key elements of highly deformable and "soft" electromechanical systems. Many of these fluid-elastomer composites utilize liquid metal alloys because of their high conductivities and inherent compliance. Understanding how these alloys interface with surfaces of various composition and texture is critical to the development of parallel processing technology, which is needed to create more complex and low-cost systems. In this work, we explore the wetting behaviors between droplets of gallium-indium alloys and thin metal films, with an emphasis on tin and indium substrates. We find that metallic droplets reactively wet thin metal foils, but the wettability of the foils may be tuned by the surface texture (produced by sputtering). The effects of both composition and texture of the substrate on wetting dynamics are quantified by measuring contact angle and droplet contact diameter as a function of time. Finally, we apply the Cassie-Baxter model to the sputtered and native substrates to gain insight into the behavior of liquid metals and the role of the oxide formation during interfacial processes. PMID:24358994

Kramer, Rebecca K; Boley, J William; Stone, Howard A; Weaver, James C; Wood, Robert J

2014-01-21

17

Shear strain mediated magneto-electric effects in composites of piezoelectric lanthanum gallium silicate or tantalate and ferromagnetic alloys  

NASA Astrophysics Data System (ADS)

Shear strain mediated magneto-electric (ME) coupling is studied in composites of piezoelectric Y-cut lanthanum gallium silicate (LGS) or tantalate (LGT) and ferromagnetic Fe-Co-V alloys. It is shown that extensional strain does not result in ME effects in these layered composites. Under shear strain generated by an ac and dc bias magnetic fields along the length and width of the sample, respectively, strong ME coupling is measured at low-frequencies and at mechanical resonance. A model is discussed for the ME effects. These composites of Y-cut piezoelectrics and ferromagnetic alloys are of importance for shear strain based magnetic field sensors.

Sreenivasulu, G.; Qu, P.; Piskulich, E.; Petrov, V. M.; Fetisov, Y. K.; Nosov, A. P.; Qu, Hongwei; Srinivasan, G.

2014-07-01

18

Controlled Electrochemical Synthesis Of Giant Magnetostrictive Iron-Gallium Alloy Thin Films And Nanowires  

NASA Astrophysics Data System (ADS)

Magnetostrictive Galfenol (Fe1-xGax, x = 10%--40%) alloys have generated tremendous interest in recent times because of their potential as functional materials in various micro- and nano-electromechanical systems (MEMS/NEMS)-based transducers and sensors. Among the giant magnetostrictive alloys, Terfenol-D (Tb1-xDyxFe2) has the largest magnetostriction, but its brittle nature limits its applications. In contrast, the next best magnetostrictive alloy, Galfenol, is highly malleable and ductile while having the tensile strength of Iron. Electrochemistry is an economical route to fabricate 'very thick' films (upto several microns) or high-aspect ratio structures like nanowire arrays. However, the highly electropositive nature of gallium makes it very difficult to electrodeposit from aqueous solutions, similar in behavior to other non-ideal elements like molybdenum, phosphorus, tungsten etc. As a result, Fe1-xGa x alloy plating has been severely plagued by non-repeatability in compositions from growth to growth, lack of uniformity in filling of pores when growing nanowires in nanoporous templates, undesired secondary hydrogen evolution reactions etc. In this study, a thorough understanding of the complex interplay between various deposition parameters (pH, overpotential, concentration, hydrodynamic conditions) was achieved, leading to an understanding of the deposition mechanism itself, thus allowing excellent control and ability to tune the alloy compositions. Arrays of nanowires were fabricated with alternating segments of the magnetostrictive alloy Fe1-xGax and Cu in nanoporous anodic aluminum oxide (AAO) templates. A novel rotating disk electrode-template (designed in-house) was used to optimize the nanowire length distributions by controlling the various aspects of electrodeposition like nucleation, kinetics and mass-transfer. Extensive structural characterization was done by X-ray diffraction (XRD), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), and magnetic characterization by vibrating sample magnetometry (VSM). Furthermore, of excellent promise in semiconductor spintronics, the feasibility of fabricating epitaxially nucleated Fe1-xGax thin films on GaAs having the desired (001) texture was demonstrated. Structural characterization using microdiffraction, high resolution ? - 2theta and rocking curve analysis revealed that the films grown on GaAs(001) are highly textured with <001> orientation along the substrate normal, and the texture improved further upon annealing at 300 °C for 2 hours in N2 environment. This was in contrast to films grown on polycrystalline brass substrates which exhibited undesired <011> texture out-of-plane. Rocking curve analysis on Fe1-xGax/GaAs structures further confirmed that the <001> texture in the Fe1-xGax thin film was indeed due to epitaxial nucleation and growth. A non-linear current-voltage plot was obtained for the Fe1-xGax/GaAs Schottky contacts, characteristic of tunneling injection, and showed improved behavior with annealing.

Reddy, Kotha Sai Madhukar

19

Study of uranium solubility in gallium-indium eutectic alloy by emf method  

NASA Astrophysics Data System (ADS)

Activity, activity coefficients and solubility of uranium in Ga-In eutectic alloy as well as activity of uranium in U-Ga and U-In alloys were determined between 573 and 1073 K using electromotive force (emf) method.

Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Osipenko, A. G.; Raspopin, S. P.; Kormilitsyn, M. V.

2013-02-01

20

Kinetics for the reaction of hydrogen with a plutonium-1 weight percent gallium alloy powder  

Microsoft Academic Search

Kinetics for the reaction of hydrogen with plutonium-1 w\\/o gallium were measured using powder prepared ''in situ.'' The rates obeyed a first-order rate law and were independent of temperature from -29\\/degree\\/ to 355\\/degree\\/C. A pressure dependence proportional to P\\/sup \\/\\/one-half\\/ was observed at pressures less than 1 kPa. From 1 to 70 kPa the pressure dependence rapidly decreased. Total pressure

Jerry L. Stakebake

1981-01-01

21

Kinetics for the reaction of hydrogen with a plutonium-1 weight percent gallium alloy powder  

SciTech Connect

Kinetics for the reaction of hydrogen with plutonium-1 w/o gallium were measured using powder prepared ''in situ.'' The rates obeyed a first-order rate law and were independent of temperature from -29/degree/ to 355/degree/C. A pressure dependence proportional to P/sup //one-half/ was observed at pressures less than 1 kPa. From 1 to 70 kPa the pressure dependence rapidly decreased. Total pressure dependence could be accurately described by a Langmuir equation. Results indicate an adsorption-controlled reaction at low pressures and a reaction-controlled process at high pressure. 19 refs.

Stakebake, J.L.

1981-11-01

22

Gallium and gallium arsenide  

SciTech Connect

As part of the Nation's growing concern with the competitiveness of U.S. firms in the world economy, especially with respect to advanced materials, the Bureau of Mines assessed the actual and potential recovery and manufacturing capabilities for gallium and gallium arsenide (GaAs). GaAs has advanced from a laboratory curiosity to a material with important high-tech applications within only the last few years, and although protected North American gallium supplies are currently considered adequate, consumption could grow to the point that this assessment would need reevaluation.

Kramer, D.

1988-01-01

23

Effects of the substitution of gallium with boron on the physical and mechanical properties of Ni-Mn-Ga shape memory alloys  

NASA Astrophysics Data System (ADS)

The effects of the substitution of gallium with boron on the physical, mechanical and magnetic shape memory properties of Ni51Mn28.5Ga20.5-x B x (at.%) (x = 0, 1, 2, 3) polycrystalline alloys are investigated. It has been found that transformation temperatures are decreasing while hardness is increasing with boron addition. B-doping of NiMnGa alloys results in the formation of a second phase that increases its ductility and strength in compression. Moreover, saturation magnetization of austenite is decreasing, while Curie temperature of austenite is increasing with B-doping.

Aydogdu, Yildirim; Turabi, Ali Sadi; Kok, Mediha; Aydogdu, Ayse; Tobe, Hirobumi; Karaca, Haluk Ersin

2014-07-01

24

Thermodynamics of reaction of praseodymium with gallium-indium eutectic alloy  

NASA Astrophysics Data System (ADS)

Thermodynamic properties of Ga-In eutectic alloys saturated with praseodymium were determined for the first time employing the electromotive force method. The equilibrium potentials of the Pr-In alloys saturated with praseodymium (8.7-12.1 mol.% Pr) and Pr-Ga-In alloys (containing 0.0012-6.71 mol.% Pr) were measured between 573-1073 K. Pr-In alloy containing solid PrIn3 with known thermodynamic properties was used as the reference electrode when measuring the potentials of ternary Pr-In-Ga alloys. Activity, partial and excessive thermodynamic functions of praseodymium in alloys with indium and Ga-In eutectic were calculated. Activity (a), activity coefficients (?) and solubility (X) of praseodymium in the studied temperature range can be expressed by the following equations: lga?-Pr(In) = 4.425 - 11965/T ± 0.026. lg??-Pr(Ga-In) = 5.866 - 14766/T ± 0.190. lg??-Pr(Ga-In) = 2.351 - 9996/T ± 0.39. lg?Pr(Ga-In) = 3.515 - 4770/T ± 0.20.

Melchakov, S. Yu.; Ivanov, V. A.; Yamshchikov, L. F.; Volkovich, V. A.; Osipenko, A. G.; Kormilitsyn, M. V.

2013-06-01

25

Hort-Range Wetting at Liquid Gallium-Bismuth Alloy Surfaces: X-ray Measurements and Square-Gradient Theory  

SciTech Connect

We present an x-ray reflectivity study of wetting at the free surface of the binary liquid metal alloy gallium-bismuth (Ga-Bi) in the region where the bulk phase separates into Bi-rich and Ga-rich liquid phases. The measurements reveal the evolution of the microscopic structure of the wetting films of the Bi-rich, low-surface-tension phase along several paths in the bulk phase diagram. The wetting of the Ga-rich bulk's surface by a Bi-rich wetting film, the thickness of which is limited by gravity to only 50 Angstroms, creates a Ga-rich/Bi-rich liquid/liquid interface close enough to the free surface to allow its detailed study by x rays. The structure of the interface is determined with Angstromsngstrem resolution, which allows the application of a mean-field square gradient model extended by the inclusion of capillary waves as the dominant thermal fluctuations. The sole free parameter of the gradient model, the influence parameter K, that characterizes the influence of concentration gradients on the interfacial excess energy, is determined from our measurements. This, in turn, allows a calculation of the liquid/liquid interfacial tension, and a separation of the intrinsic and capillary wave contributions to the interfacial structure. In spite of expected deviations from MF behavior, based on the upper critical dimensionality (Du = 3 ) of the bulk, we find that the capillary wave excitations only marginally affect the short-range complete wetting behavior. A critical wetting transition that is sensitive to thermal fluctuations appears to be absent in this binary liquid-metal alloy.

Huber, P.; Shpyrko, O; Pershan, P; Ocko, B; DiMasi, E; Deutsch, M

2009-01-01

26

Magnetostriction and texture development in binary and ternary iron-gallium-based alloys  

NASA Astrophysics Data System (ADS)

The rare earth-free bcc FeGa-based alloys have an excellent combination of large low-field magnetostriction at room temperature, good mechanical properties, low hysteresis, and relatively low cost. These alloys are attractive for use in numerous sensor and actuator devices. The first part of this dissertation examines the influence of partial substitutions of Ga with Al, Be, Si, Ge, and Sn and partial substitutions of Fe with Co and Ni. The work involved directional growth of [001] textured rods of these ternary alloys using a Vertical Bridgman process, X-ray diffraction analysis, magnetic property measurements using vibrating sample magnetometry, and magnetostriction measurements. It is shown that substitution of Ga with Al can be made in FeGa alloys in certain composition ranges without a reduction in magnetostriction, and the additions of Si, Ge, and Sn results in a sharp decrease of magnetostriction. The addition or substitute of Be, due to its smaller size than Fe, resulted in only a slight decrease of magnetostriction. Substitution of Fe with Ni and Co results in a significant decrease of the magnetostriction. The work also evaluated the elastic properties of Fe-x at. % Ga and Fe-(20-y) at. % Ga-y at. % Al polycrystalline alloys using resonant ultrasound spectroscopy. Young's modulus obtained for FeGa and FeGaAl alloys were in the range of 110 to 170 GPa which are several times that for Terfenol-D alloys. Thus, large-force delivery is possible from FeGa alloy based actuators even though saturation strain values are smaller than that of Terfenol-D. The second part of this work examined the development of an inexpensive thermomechanical processing method to obtain [001] textured polycrystalline Fe-15 at. % Ga alloys. The processing involved a sequence of controlled hot rolling, two-stage warm rolling with intermediate anneal, and texture anneal. Roll forces measured and the extent of reductions feasible indicated an excellent processability. Texture evolution during different stages of processing was examined using Orientation Imaging Microscopy to identify conditions that favor [001] texture development. The results indicate that addition of 1 mol.% NbC and controlled process conditions lead to a very strong [001] texture.

Mungsantisuk, Pinai

27

Iron-gallium alloys : temperature and field effects on [lambda]100 and magnetic anisotropy measurements  

E-print Network

Magnetostriction measurements were taken on samples of Fe-Ga alloys (Galfenol) containing between 18% and 35% Ga in fields of 5 kOe to 24 kOe from room temperature to liquid nitrogen temperature. In addition, room temperature ...

Lichter, Jenny, 1982-

2004-01-01

28

Gallium scan  

MedlinePLUS

... material called gallium and is a type of nuclear medicine exam. A related test is gallium scan of ... Segerman D, Miles KA. Radionuclide imaging: general principles. ... Diagnostic Radiology: A Textbook of Medical Imaging . 5th ed. New ...

29

Measurement of field-dependence elastic modulus of iron-gallium alloy using tensile test  

SciTech Connect

An experimental approach is used to identify Galfenol material properties under dc magnetic bias fields. Dog-bone-shaped specimens of single crystal Fe{sub 100-x}Ga{sub x}, where 18.6{<=}x{<=}33.2, underwent tensile testing along two crystallographic axis orientations, [110] and [100]. Young's modulus and Poisson's ratio sensitivity to magnetic fields and stoichiometry are investigated. Data are presented that demonstrate the dependence of these properties on applied magnetic-field levels and provide a substantial assessment of the trends in material properties for performance of alloys of different stoichiometries under varied operating conditions.

Yoo, Jin-Hyeong; Flatau, Alison B. [University of Maryland, College Park, Maryland 20742 (United States)

2005-05-15

30

Native point defects in indium nitride and indium-rich indium gallium nitride alloys  

NASA Astrophysics Data System (ADS)

The recent discovery of the narrow bandgap of InN of 0.7 eV has attracted strong scientific interests on the fundamental properties and possible applications of InN and its ternary alloys. The first part of this thesis was inspired by the proposal of using InxGa1-x N alloy to build high efficiency solar cell for space applications. To test the irradiation hardness of InN and InxGa 1-xN, we have irradiated numerous samples with energetic particles (1-2 MeV electrons, protons, and 4He+ particles). InN and InxGa1-xN displayed superior radiation hardness over current multi-junction solar cell materials such as GaAs and GaInP in terms of electronic and optical properties. Free electron concentrations in InN and In-rich InxGa 1-xN increased with irradiation dose but saturated at a sufficiently high damage dose. According to the amphoteric defect model, the doping effect and the electron concentration saturation originates from irradiation-induced native donors and Fermi level pinning at the Fermi level stabilization energy (EFS). The EFS, an average energy of all localized native defects, dictates the electronic properties (donor or acceptor) of the native point defects. The electron concentration saturation and Fermi level pinning lead to profound changes in the optical properties. Absorption spectra shift to higher energy due to the conduction band-filling effect (Burstein-Moss shift). Photoluminescence (PL) signals broadened and shifted to higher energy as the k-conservation rule collapsed with irradiation damage. The PL intensity of increased slightly with higher carrier concentration before it became quenched by the irradiation-induced carrier traps. Capacitance-voltage (CV) measurements show that the pinning of the surface Fermi energy at EFS is also responsible for the surface electron accumulation effect in InN and In-rich In xGa1-xN alloys. The second part of this thesis focuses on the hydrostatic pressure dependence of group III-nitride alloys. The hydrostatic pressure dependence of the narrow bandgap of InN, In-rich InxGa1-x N (0 < x ? 0.5), and InyAl 1-yN (y = 0.25) alloys was measured by optical absorption and PL experiments with samples mounted in diamond anvil cells. The pressure coefficient of InN was experimentally determined for the first time to be 3.0+/-0.1 meV/kbar. The PL signal exhibits a much weaker pressure dependence than the direct bandgap, which is attributed to the emission process associated with highly localized states. Using the localized states emission as an energy reference, the deformation potential of the band edges of InN and In0.5Ga0.5N were determined.

Li, Sonny Xiao-Zhe

31

Evaluation of magnetostrictive shunt damper performance using Iron (Fe)-Gallium (Ga) alloy  

NASA Astrophysics Data System (ADS)

This study presents the possibility of dissipating mechanical energy with a proof-of-concept prototype magnetostrictive based shunt circuit using passive electrical components. The device consists of a polycrystalline galfenol (Fe-Ga alloy) strip bonded to a brass cantilever beam. Two brass pieces, each containing a permanent magnet, are used to mass load each end of the beam and to provide a magnetic bias field through the galfenol strip. The voltage induced in an induction coil closely wound around the cantilever beam captures the time rate of change of magnetic flux within the galfenol strip as the beam vibrates. The first bending-mode resonant frequency of the device was 69.42 Hz. To dissipate the electrical voltage from the device, a shunt circuit is attached. The effective mechanical impedance for the magnetostrictive shunt circuit is derived. The shunted model is specialized for two shunt circuits: the case of a resistor and that of a capacitance. The experimental results for both the resistive and capacitance shunt circuits validate the shunted magnetostrictive damping model for couple of cased of resistance and capacitance.

Yoo, JinHyeong; Murray, Andrew; Flatau, Alison B.

2014-04-01

32

The influence of indium and gallium on the lattice spacings of the ?? and ? phases of the silver-zinc alloys  

Microsoft Academic Search

Accurate measurements have been made of the lattice spacings of the ?? and ? phases of AgZnIn alloys, and of the ? phase of AgZnGa and AgGa alloys. In the AgZnIn alloys, which contained up to 3·65 at. % indium, the axial ratio of the ? phase is always close to that of the binary alloy of the same electron

W. D. Hoff; R. P. Stratton; W. J. Kitchingman

1964-01-01

33

Grain boundary imaging, gallium diffusion and the fracture behavior of Al–Zn Alloy – An in situ study  

Microsoft Academic Search

Phase contrast radiology using unmonochromatic synchrotron X-ray successfully imaged the grain boundaries of Al and AlZn alloy without contrast agent. Combining the high penetration of X-ray and the possibility of 3D reconstruction by tomorgraphy or stereography method, this approach can be very used for nondestructive characterization of polycrystalline materials. By examine the images with 3D perspective, we were able locate

W. L. Tsai; Y. Hwu; C. H. Chen; L. W. Chang; J. H. Je; H. M. Lin; G. Margaritondo

2003-01-01

34

Grain boundary imaging, gallium diffusion and the fracture behavior of Al-Zn Alloy - An in situ study  

Microsoft Academic Search

Phase contrast radiology using unmonochromatic synchrotron X-ray successfully imaged the grain boundaries of Al and AlZn alloy without contrast agent. Combining the high penetration of X-ray and the possibility of 3D reconstruction by tomorgraphy or stereography method, this approach can be very used for nondestructive characterization of polycrystalline materials. By examine the images with 3D perspective, we were able locate

W. L. Tsai; Y. Hwu; C. H. Chen; L. W. Chang; J. H. Je; H. M. Lin; G. Margaritondo

2003-01-01

35

Bismuth in gallium arsenide: Structural and electronic properties of GaAs{sub 1-x}Bi{sub x} alloys  

SciTech Connect

The structural and electronic properties of cubic GaAs{sub 1-x}Bi{sub x} alloys with bismuth concentration 0.0, 0.25, 0.50, 0.75 and 1.0 are studied using the 'special quasi-random structures' (SQS) approach of Zunger along with the generalized gradient approximation (GGA) and the Engel-Vosko generalized gradient approximation (EV-GGA). The lattice constant, bulk modulus, derivative of bulk modulus and energy gap vary with bismuth concentration nonlinearly. The present calculations show that the band gap decreases substantially with increasing bismuth concentration and that spin-orbit coupling influences the nature of bonding at high Bi concentrations. - Graphical abstract: Bowing effect of spin-orbit split-off band values versus Bi content with and without spin-orbit coupling for GaAs{sub 1-x}Bi{sub x} (at x=0.25, 0.50 and 0.75). Calculations are done with GGA. Highlights: Black-Right-Pointing-Pointer Structural and electronic properties of GaAs{sub 1-x}Bi{sub x} alloys were studied. Black-Right-Pointing-Pointer We present results of lattice constant, energy gap, bulk modulus and derivative. Black-Right-Pointing-Pointer The band gap decreases substantially with increasing Bi concentration. Black-Right-Pointing-Pointer Calculations of the density of states and charge densities are also presented. Black-Right-Pointing-Pointer We have performed calculations without and with spin-orbit coupling.

Reshak, Ali Hussain, E-mail: maalidph@yahoo.co.uk [School of Complex Systems, FFWP-South Bohemia University, Nove Hrady 37333 (Czech Republic); School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Kamarudin, H. [School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Auluck, S. [National Physical Laboratory Dr. KS Krishnan Marg, New Delhi 110012 (India); Kityk, I.V. [Electrical Engineering Department, Technological University of Czestochowa, Al. Armii Krajowej 17/19, Czestochowa (Poland)

2012-02-15

36

Optical and electrical characterization of melt-grown bulk indium gallium arsenide and indium arsenic phosphide alloys  

NASA Astrophysics Data System (ADS)

Optical and electrical properties of bulk melt-grown ternary InAs 1-yPy and InxGa1-xAs polycrystals were investigated as functions of phosphorus and indium compositions and temperatures using the photoluminescence, Fourier transform infrared (FTIR) transmission spectrum, refractive index, and Hall-effect measurements. These ternary alloys were grown using the vertical Bridgman techniques. The as-grown undoped bulk ternary InAs1-yPy and InxGa1-xAs polycrystals have been found to exhibit n-type conductivity irrespective of the alloy compositions possibly due to residual impurities and native defects. In general, carrier concentrations and Hall mobilities increase with the indium composition for InxGa1-xAs, whereas they decrease with increasing phosphorus mole fraction for the InAs1-yPy sample. The FTIR spectra of all these ternary samples demonstrated good infrared transmission. A systematic measurement of photoluminescence was carried out in order to gain insight into the various radiative transitions in the InAs1-yPy and InxGa1-xAs crystals, which include the temperature, laser excitation power, and sample location dependent studies. The wavelength, temperature, and composition dependent refractive indices of InAs1-y Py and InxGa1-xAs were studied using minimum deviation and Michelson Fabry-Perot interferometry methods. The measured results of refractive indices, transport properties, bandgap energies, and optical transmissions are presented here as functions of alloy composition, temperature and photon energy for the first time, to the best of our knowledge. Although the bulk InAs1-yPy and In xGa1-xAs samples show good optical transmissions, PL transitions, and high carrier mobilities, they do exhibit some random compositional fluctuations across the sample. A practical method of extracting bandgap energies directly from the FTIR transmission spectra has been presented in this work, and the results are promising even though further refinement is required. Bandgap energies estimated from the transmission spectra agree well with those obtained from PL spectra and the previously reported values from the thin film studies. Overall, the optical and electrical properties of these crystals are well suited for a variety of device applications that do not require single crystalline material.

Wei, Jean

37

Compatibility of ITER candidate structural materials with static gallium  

SciTech Connect

Tests were conducted on the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor, e.g., Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy, as well as Armco iron, Nickel 270, and pure chromium. Type 316 stainless steel is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400{degrees}C, corrosion rates are {approx}4.0, 0.5, and 0.03 mm/yr for type 316 SS, Inconel 625, and Nb-5 Mo- 1 Zr alloy, respectively. The pure metals react rapidly with gallium. In contrast to findings in earlier studies, pure iron shows greater corrosion than nickel. The corrosion rates at 400{degrees}C are {ge}88 and 18 mm/yr, respectively, for Armco iron and Nickel 270. The results indicate that at temperatures up to 400{degrees}C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The solubility data for pure metals and oxygen in gallium are reviewed. The physical, chemical, and radioactive properties of gallium are also presented. The supply and availability of gallium, as well as price predictions through the year 2020, are summarized.

Luebbers, P.R.; Michaud, W.F.; Chopra, O.K.

1993-12-01

38

Investigations in gallium removal  

SciTech Connect

Gallium present in weapons plutonium must be removed before it can be used for the production of mixed-oxide (MOX) nuclear reactor fuel. The main goal of the preliminary studies conducted at Texas A and M University was to assist in the development of a thermal process to remove gallium from a gallium oxide/plutonium oxide matrix. This effort is being conducted in close consultation with the Los Alamos National Laboratory (LANL) personnel involved in the development of this process for the US Department of Energy (DOE). Simple experiments were performed on gallium oxide, and cerium-oxide/gallium-oxide mixtures, heated to temperatures ranging from 700--900 C in a reducing environment, and a method for collecting the gallium vapors under these conditions was demonstrated.

Philip, C.V.; Pitt, W.W. [Texas A and M Univ., College Station, TX (United States); Beard, C.A. [Amarillo National Resource Center for Plutonium, TX (United States)

1997-11-01

39

Gallium nitride optoelectronic devices  

NASA Technical Reports Server (NTRS)

The growth of bulk gallium nitride crystals was achieved by the ammonolysis of gallium monochloride. Gallium nitride single crystals up to 2.5 x 0.5 cm in size were produced. The crystals are suitable as substrates for the epitaxial growth of gallium nitride. The epitaxial growth of gallium nitride on sapphire substrates with main faces of (0001) and (1T02) orientations was achieved by the ammonolysis of gallium monochloride in a gas flow system. The grown layers had electron concentrations in the range of 1 to 3 x 10 to the 19th power/cu cm and Hall mobilities in the range of 50 to 100 sq cm/v/sec at room temperature.

Chu, T. L.; Chu, S. S.

1972-01-01

40

Thermodynamic properties of uranium in Ga-In based alloys  

NASA Astrophysics Data System (ADS)

Activity of uranium was determined in gallium, indium and gallium-indium eutectic (21.8 wt.% In) based alloys between 573 and 1073 K employing the electromotive force method. In two-phase U-Ga-In alloys, uranium forms the intermetallic compound UGa3. Activity coefficients and solubility of uranium in Ga-In eutectic were also determined in the same temperature range. Partial thermodynamic functions of ?-U in saturated alloys with gallium, indium and Ga-In eutectic were calculated.

Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Melchakov, S. Yu; Shchetinskiy, A. V.; Osipenko, A. G.; Kormilitsyn, M. V.

2013-07-01

41

Properties of gallium arsenide  

SciTech Connect

Properties of Gallium Arsenide' is a handbook of evaluated numeric data and reviewed knowledge distilled by those working at the frontiers of gallium arsenide research. In addition to providing numeric data on basic physical, electronic and optical properties, the book covers many device-related aspects of gallium arsenide. Carrier attributes (ionisation coefficients, concentration, mobility, diffusion etc), deep levels and defects are surveyed and related to the various growth techniques such as MBE, VPE, and MOCVD. Sections on surface structure, oxidation, interfaces and etching are of particular relevance to integrated circuit research. Especially important in the race to achieve commercially usable samples is a state-of-the-art survey on the infra-red imaging of defects in semi-insulating gallium arsenide produced by the liquid-encapsulated Czochralski process.

Not Available

1985-01-01

42

Gallium interactions with Zircaloy  

E-print Network

: Nuclear Engineering GALLIUM INTERACTIONS WITH ZIRCALOY A Thesis by MICHAEL KEITH WEST Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: Ron R.... Hart (Chair of Co ittee) Karl T. H g, (Me e Marvin L. Adams (Member) Alan E. Waltar (Head of Department) December 1998 Major Subject: Nuclear Engineering ABSTRACT Gallium Interactions with Zircaloy. (December 1998) Michael Keith West, B. S...

West, Michael Keith

2012-06-07

43

Interactions of Zircaloy Cladding with Gallium: Final Report  

SciTech Connect

The U.S. Department of Energy has established a dual-track approach to the disposition of plutonium arising from the dismantling of nuclear weapons. Both immobilization and reactor-based mixed-oxide (MOX) fuel technologies are being evaluated. The reactor-based MOX fuel option requires assessment of the potential impact of concentrations of gallium (on the order of 1 to 10 ppm), not present in conventional MOX fhel, on cladding material performance. Three previous repmts"3 identified several compatibility issues relating to the presence of gallium in MOX fuel and its possible reaction with fiel cladding. Gallium initially present in weapons-grade (WG) plutonium is largely removed during processing to produce MOX fhel. After blending the plutonium with uranium, only 1 to 10 ppm gallium is expected in the sintered MOX fuel. Gallium present as gallium oxide (G~OJ could be evolved as the suboxide (G~O). Migration of the evolved G~O and diffusion of gallium in the MOX matrix along thermal gradients could lead to locally higher concentrations of G~03. Thus, while an extremely low concentration of gallium in MOX fiel almost ensures a lack of significant interaction of gallium whh Zircaloy fhel cladding, there remains a small probability that corrosion effects will not be negligible. General corrosion in the form of surface alloying resulting from formation of intermetallic compounds between Zircaloy and gallium should be ma& limited and, therefore, superficial because of the expected low ratio of gallium to the surface area or volume of the Zircaloy cladding. Although the expected concentration of gallium is low and there is very limited volubility of gallium in zirconium, especially at temperatures below 700 "C,4 grain boundary penetration and liquid metal embrittlement (LME) are forms of localized corrosion that were also considered. One fuel system darnage mechanism, pellet clad interaction, has led to some failure of the Zircaloy cladding in light-water reactors (LWRS). This has been attributed to stresses in the cladding and one or more aggressive fission products. Stress corrosion cracking by iodines' 6 and LME by cadmium7>8 have been reported, and it is known that Zircaloy can be embrittled by some low-melting metals, (e.g., mercury).g LME is a form of environmentally induced embrittlement that can induce cracking or loss of ductility. LME requties wetting and a tensile stress, but it does not require corrosion penetration. Experimentally, it has been demonstrated that gallium can cause embrittlement of some alloys (e.g., aluminum) at low temperatures,'"' ] ] but experiments relative to LME of zirconium by gallium have been limited and inconclusive.*2 This report describes a series of tests designed to establish the effects of low levels of residual gallium in WG-MOX fhel on its compatibility with Zircaloy. In addition, to establish damage mechanisms it was important to understand types of cladding interactions and available stiety margins with respect to gallium concentration.

D.F. Wilson; E.T. Manneschmidt; J.F. King; J.P. Strizak; J.R. DiStefano

1998-09-01

44

Amphoteric Impurities in Gallium Arsenide.  

National Technical Information Service (NTIS)

Gallium arsenide is already an important material for application in high frequency, low noise field effect transitors (FETs) and in optoelectronic devices, and future Gallium Arsenide (GaAs) high speed integrated circuits are expected to have a major imp...

G. E. Stillman

1987-01-01

45

Aluminum battery alloys  

DOEpatents

Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

Thompson, D.S.; Scott, D.H.

1984-09-28

46

Energy-based quasi-static modeling of the actuation and sensing behavior of single-crystal iron-gallium alloys  

NASA Astrophysics Data System (ADS)

An energy based model [W. D. Armstrong, J. Appl. Phys. 81, 2321 (1997); J. Atulasimha, Ph.D. thesis, Aerospace Engineering, University of Maryland, College Park, MD, 2006] is employed to predict the actuation (? -H and B -H at various compressive stresses) and sensing behavior (B -? and ? -? at various bias fields) of single-crystal FeGa alloys. The significant feature of this formulation is that, in addition to modeling actuation behavior, the sensing behavior can be predicted based on parameters estimated from the actuator characteristics. These predictions are then validated against experimental data for furnace cooled 19 at. % [100] oriented single-crystal FeGa alloys. Furthermore, an attempt is made to couple the energy-based sensing model with a lumped-parameter model that simulates the magnetic interaction between the magnetostrictive specimen and the magnetic circuit comprising the transducer. This enables a prediction of the variation in field through the sample due to changes in reluctance of the magnetostrictive sample with stress, as well as the impact of this variation in field on the B -? and ? -? curves. These predictions are benchmarked against experimental data, wherein the bias field varies due to change in sample reluctance with application of compressive stress while the drive current to the transducer is maintained constant.

Atulasima, Jayasimha; Flatau, Alison B.; Cullen, James R.

2008-01-01

47

Mechanical properties and clinical performance of a gallium restorative material.  

PubMed

In a combination clinical/laboratory evaluation, a gallium restorative alloy (Galloy) was assessed for six mechanical properties: compressive strength, diametral tensile strength, creep, hardness, wear, and dimensional change. Laboratory tests indicated that the gallium alloy was similar to either Tytin or Dispersalloy in most respects, with the exception of lower wear and higher 7-day diametral tensile strength. In the clinical trial, all Galloy restorations were lined with a resin to prevent moisture contacting the material during the first hours after placement. All gallium restorations--class 1's only--were intact, and no teeth were fractured at the end of 1 year. There was little difference found at the 1-year evaluation compared to the 6-month results. The surface of the gallium alloy was generally rough, and many restorations exhibited some tarnish on the surface. It should be pointed out that this product has not been FDA approved at the present time and is not on the market. PMID:8710706

Osborne, J W; Summitt, J B

1995-01-01

48

Design System for Locally Fabricated Gallium Arsenide  

E-print Network

Design System for Locally Fabricated Gallium Arsenide Digital Integrated Circuits by Anthony Edward, 26 November, 1990 © Anthony Parker 1990 Gallium Arsenide Digital Integrated Circuits Project System for Locally Fabricated Gallium Arsenide Digital Integrated Circuits A thesis submitted to Sydney

49

Designing Asynchronous Circuits in Gallium Arsenide  

E-print Network

Designing Asynchronous Circuits in Gallium Arsenide Jos'e A. Tierno Department of Computer Science.1 Asynchronous circuits : : : : : : : : : : : : : : : : : : : : : : : 4 1.2 Gallium Arsenide : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 6 1.5 Outline of this Thesis : : : : : : : : : : : : : : : : : : : : : : : 6 2 Gallium Arsenide

Martin, Alain

50

Gallium-containing anticancer compounds  

PubMed Central

There is an ever pressing need to develop new drugs for the treatment of cancer. Gallium nitrate, a group IIIa metal salt, inhibits the proliferation of tumor cells in vitro and in vivo and has shown activity against non-Hodgkin’s lymphoma and bladder cancer in clinical trials. Gallium can function as an iron mimetic and perturb iron-dependent proliferation and other iron-related processes in tumor cells. Gallium nitrate lacks cross resistance with conventional chemotherapeutic drugs and is not myelosuppressive; it can be used when other drugs have failed or when the blood count is low. Given the therapeutic potential of gallium, newer generations of gallium compounds are now in various phases of preclinical and clinical development. These compounds hold the promise of greater anti-tumor activity against a broader spectrum of cancers. The development of gallium compounds for cancer treatment and their mechanisms of action will be discussed. PMID:22800370

Chitambar, Christopher R

2013-01-01

51

Structural characteristics of gallium metal deposited on Si (0 0 1) by MOCVD  

NASA Astrophysics Data System (ADS)

The epitaxial growth of high quality gallium containing III/V material on silicon offers a wide field of possible applications. While the growth of III/V material has already been studied extensively, little is known about the atomic processes at the interface between silicon and the III/V material. Here we study the deposition of gallium on silicon (0 0 1) by metal organic chemical vapour deposition for the two different precursors triethyl gallium and trimethyl gallium, the influence of varying growth conditions as well as the influence of an annealing after growth. We use atomic force microscopy and high angle annular dark field scanning transmission electron microscopy to analyse the detailed structures occurring for this deposition. For all conditions studied, pyramidal gallium containing structures form in the silicon with boundaries on the silicon {1 1 1} lattice planes. The pyramidal etching structures can be reproduced in straightforward kinetic Monte Carlo simulations of the growth process. When triethyl gallium is used, those structures are covered by carbon containing passivating mounds. After an additional annealing at 800 °C no gallium can be detected anymore for any sample, while an annealing at considerably lower temperatures leads to an alteration of the silicon gallium alloy.

Werner, K.; Beyer, A.; Oelerich, J. O.; Baranovskii, S. D.; Stolz, W.; Volz, K.

2014-11-01

52

Compatibility of ITER candidate materials with static gallium  

SciTech Connect

Corrosion tests have been conducted to determine the compatibility of gallium with candidate structural materials for the International Thermonuclear Experimental Reactor (ITER) first wall/blanket systems, e.g., Type 316 stainless steel (SS), Inconel 625, and Nb-5 Mo-1 Zr. The results indicate that Type 316 SS is least resistant to corrosion in static gallium and Nb-5 Mo-1 Zr alloy is most resistant. At 400 C, corrosion rates for Type 316 SS, Inconel 625, and Nb-5 Mo-1 Zr alloy are {approx} 4.0, 0.5, and 0.03 mm/yr, respectively. Iron, nickel, and chromium react rapidly with gallium. Iron shows greater corrosion than nickel at 400 C ({ge} 88 and 18 mm/yr, respectively). The present study indicates that at temperatures up to 400 C, corrosion occurs primarily by dissolution and is accompanied by formation of metal/gallium intermetallic compounds. The growth of intermetallic compounds may control the overall rate of corrosion.

Luebbers, P.R.; Chopra, O.K. [Argonne National Lab., IL (United States). Energy Technology Div.

1995-09-01

53

Gallium phosphide energy converters  

Microsoft Academic Search

Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need

P. E. Sims; L. C. Dinetta; M. A. Goetz

1995-01-01

54

Alloy  

NASA Astrophysics Data System (ADS)

The Mg98.5Gd1Zn0.5 alloy produced by a powder metallurgy route was studied and compared with the same alloy produced by extrusion of ingots. Atomized powders were cold compacted and extruded at 623 K and 673 K (350 °C and 400 °C). The microstructure of extruded materials was characterized by ?-Mg grains, and Mg3Gd and 14H-LPSO particles located at grain boundaries. Grain size decreased from 6.8 ?m in the extruded ingot, down to 1.6 ?m for powders extruded at 623 K (350 °C). Grain refinement resulted in an increase in mechanical properties at room and high temperatures. Moreover, at high temperatures the PM alloy showed superplasticity at high strain rates, with elongations to failure up to 700 pct.

Cabeza, Sandra; Garcés, Gerardo; Pérez, Pablo; Adeva, Paloma

2014-07-01

55

Oxidative dissolution of gallium arsenide and separation of gallium from arsenic  

SciTech Connect

The method of dissociating gallium arsenide into a gallium-containing component and an arsenic-containing component, is described which comprises contacting the gallium arsenide with an oxidizing agent and a liquid comprising hydroxamic acid to convert the gallium to a gallium-hydroxamic acid complex and to oxidize the arsenic to a positive valence state.

Coleman, J.P.; Monzyk, B.F.

1988-07-26

56

Fabrication of Aluminum Gallium Nitride/Gallium Nitride MESFET And It's Applications in Biosensing  

NASA Astrophysics Data System (ADS)

Gallium Nitride has been researched extensively for the past three decades for its application in Light Emitting Diodes (LED's), power devices and UV photodetectors. With the recent developments in crystal growth technology and the ability to control the doping there has been an increased interest in heterostructures formed between Gallium nitride and it's alloy Aluminium Gallium Nitride. These heterostructures due to the combined effect of spontaneous and piezoelectric effect can form a high density and a high mobility electron gas channel without any intentional doping. This high density electron gas makes these heterostructures ideal to be used as sensors. Gallium Nitride is also chemically very stable. Detection of biomolecules in a fast and reliable manner is very important in the areas of food safety and medical research. For biomolecular detection it is paramount to have a robust binding of the probes on the sensor surface. Therefore, in this dissertation, the fabrication and application of the AlGaN/GaN heterostructures as biological sensors for the detection of DNA and Organophosphate hydrolase enzyme is discussed. In order to use these AlGaN/GaN heterostructures as biological sensors capable of working in a liquid environment photodefinable polydimethyl-siloxane is used as an encapsulant. The immobilization conditions for a robust binding of thiolated DNA and the catalytic receptor enzyme organophosphate hydrolase on gold surfaces is developed with the help of X-ray photoelectron spectroscopy. DNA and OPH are detected by measuring the change in the drain current of the device as a function of time.

Alur, Siddharth

57

Gallium phosphide energy converters  

NASA Technical Reports Server (NTRS)

Betavoltaic power supplies based on gallium phosphide can supply long term low-level power with high reliability. Results are presented for GaP devices powered by Ni-63 and tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/cm(exp 2) have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. A small demonstration system has been assembled that generates and stores enough electricity to light up an LED.

Sims, P. E.; DiNetta, Louis C.; DuganCavanagh, K.; Goetz, M. A.

1996-01-01

58

Gallium interstitial contributions to diffusion in gallium arsenide  

NASA Astrophysics Data System (ADS)

A new diffusion path is identified for gallium interstitials, which involves lower barriers than the barriers for previously identified diffusion paths [K. Levasseur-Smith and N. Mousseau, J. Appl. Phys. 103, 113502 (2008), P. A. Schultz and O. A. von Lilienfeld, Modelling and Simulation in Materials Science and Engineering 17, 084007 (2009)] for the charge states which dominate diffusion over most of the available range of Fermi energies. This path passes through the ?110? gallium-gallium split interstitial configuration, and has a particularly low diffusion barrier of 0.35 eV for diffusion in the neutral charge state. As a part of this work, the character of the charge states for the gallium interstitials which are most important for diffusion is investigated, and it is shown that the last electron bound to the neutral interstitial occupies a shallow hydrogenic bound state composed of conduction band states for the hexagonal interstitial and both tetrahedral interstitials. How to properly account for the contributions of such interstitials is discussed for density-functional calculations with a k-point mesh not including the conduction band edge point. Diffusion barriers for gallium interstitials are calculated in all the charge states which can be important for a Fermi level anywhere in the gap, q = 0, +1, +2, and +3, for diffusion via the ?110? gallium-gallium split interstitial configuration and via the hexagonal interstitial configuration. The lowest activation enthalpies over most of the available range of Fermi energies are found to correspond to diffusion in the neutral or singly positive state via the ?110? gallium-gallium split interstitial configuration. It is shown that several different charge states and diffusion paths contribute significantly for Fermi levels within 0.2 eV above the valence band edge, which may help to explain some of the difficulties [H. Bracht and S. Brotzmann, Phys. Rev. B 71, 115216 (2005)] which have been encountered in fitting experimental results for heavily p-type, Ga-rich gallium arsenide by simply extending a model for gallium interstitial diffusion which has been used for less p-doped material.

Schick, Joseph T.; Morgan, Caroline G.

2011-09-01

59

The interaction of gold with gallium arsenide  

NASA Technical Reports Server (NTRS)

Gold and gold-based alloys, commonly used as solar-cell contact materials, are known to react readily with gallium arsenide. Experiments designed to identify the mechanisms involved in these GaAs-metal interactions have yielded several interesting results. It is shown that the reaction of GaAs with gold takes place via a dissociative diffusion process. It is shown further that the GaAs-metal reaction rate is controlled to a very great extent by the condition of the free surface of the contact metal, an interesting example of which is the previously unexplained increase in the reaction rate that has been observed for samples annealed in a vacuum environment as compared to those annealed in a gaseous ambient. A number of other hard-to-explain observations, such as the low-temperature formation of voids in the gold lattice and crystallite growth on the gold surface, are also explained by invoking this mechanism.

Weizer, Victor G.; Fatemi, Navid S.

1988-01-01

60

Contact formation in gallium arsenide solar cells  

NASA Technical Reports Server (NTRS)

Gold and gold-based alloys, commonly used as solar cell contact materials, are known to react readily with gallium arsenide. Experiments were performed to identify the mechanisms involved in these GaAs-metal interactions. It is shown that the reaction of GaAs with gold takes place via a dissociative diffusion process. It is shown further that the GaAs-metal reaction rate is controlled to a very great extent by the condition of the free surface of the contact metal, an interesting example of which is the previously unexplained increase in the reaction rate that has been observed for samples annealed in a vacuum environment as compared to those annealed in a gaseous ambient. A number of other hard-to-explain observations, such as the low-temperature formation of voids in the gold lattice and crystallite growth on the gold surface, are explained by invoking this mechanism.

Weizer, Victor G.; Fatemi, Navid S.

1988-01-01

61

GALLIUM--1997 29.1 By Deborah A. Kramer  

E-print Network

devices manufactured from gallium arsenide (GaAs) continued to be the principal use for gallium. Increased. These epitiaxial layers are normally gallium aluminum arsenide (GaAlAs), gallium arsenide phosphide (GaAsP), or indium gallium arsenide phosphide (InGaAsP), while the substrate material is either GaAs or gallium

62

Potential of gallium-based leads for cardiac rhythm management devices  

Microsoft Academic Search

We propose the use of gallium (Ga), a metal that is liquid at physiological temperatures, or one of its alloys, for use as the conducting material in the leads of implantable pacemakers or cardioverter defibrillators. It is proposed that a liquid conductor will make these leads more pliable and thus less susceptible to fracture in situ. As an initial step

Aaron M. Kyle; Nichole Leahy-Glass; William Combs; Keith L. March

2011-01-01

63

Gallium localization in peritonitis. Two case reports  

SciTech Connect

Diffuse abdominal localization of gallium was found in two patients with peritonitis, one due to M. tuberculosis and the other presumably pyogenic. Gallium scanning may be useful in the diagnosis of peritonitis and perhaps of other serosal infections.

LaManna, M.M.; Saluk, P.H.; Zekavat, P.P.; Mobini, J.; Parker, J.A.

1984-01-01

64

Simulating the Atomic Assembly of Gallium Arsenide  

E-print Network

Simulating the Atomic Assembly of Gallium Arsenide A Dissertation Presented to the Faculty with gallium-rich GaAs (001) surfaces indicate a high sticking probability for SW potentials. This is in good an orientation dependence. Atomic processes responsible for the formation of the gallium vacancy defects were

Wadley, Haydn

65

Examples of liquiq metal embrittlement in industrial aluminium alloys  

Microsoft Academic Search

Liquid metal embrittlement (LME) phenomena were investigated in two industrial aluminium alloys. Gallium penetration in 7010 alloys was systematically investigated to shed light on the effect of microstructure and plasticity ahead of the crack tip. Hot temperature shortness in 5083 alloy is given as an example of cleavage induced by LME.

Y. Bréchet; A. Rodine; M. Véron; S. Péron; A. Deschamps

2002-01-01

66

Progress in gallium arsenide semiconductors  

SciTech Connect

After almost 30 years as the technology of the future, gallium arsenide has begun to make a place for itself, not by supplanting silicon but by complementing it in new applications. The inherent advantages of the material lie in the speed with which electrons move through it, in weak-signal operations and in the generation and detection of light. These advantages suit it for roles in computing, television reception and the optoelectronic transmission of data through optical-fiber networks. Gallium arsenide light-emitting diodes and lasers used in visual-display technologies and audio-disk players already account for more than $1 billion in sales annually. Hundreds of thousands of satellite-receiving dishes that use gallium arsenide detectors are sold every year, and high-speed circuits using gallium arsenide transistors are projected to reach a similar turnover in a few years. In an economy and society that depend on the rapid exchange of information as well as on the processing of it, many silicon-dominated processors will require a considerable admixture of gallium arsenide components in order to do their jobs.

Brodsky, M.H. (IBM Thomas J. Watson Research Center, Yorktown Heights, NY (USA))

1990-02-01

67

Effect of oxidation on the Mechanical Properties of Liquid Gallium and Eutectic Gallium-Indium  

E-print Network

Liquid metals exhibit remarkable mechanical properties, in particular large surface tension and low viscosity. However, these properties are greatly affected by oxidation when exposed to air. We measure the viscosity, surface tension, and contact angle of gallium (Ga) and a eutectic gallium-indium alloy (eGaIn) while controlling such oxidation by surrounding the metal with an acid bath of variable concentration. Rheometry measurements reveal a yield stress directly attributable to an oxide skin that obscures the intrinsic behavior of the liquid metals. We demonstrate how the intrinsic viscosity can be obtained with precision through a scaling technique that collapses low- and high-Reynolds number data. Measuring surface tension with a pendant drop method, we show that the oxide skin generates a surface stress that mimics surface tension and develop a simple model to relate this to the yield stress obtained from rheometry. We find that yield stress, surface tension, and contact angle all transition from solid-like to liquid behavior at the same critical acid concentration, thereby quantitatively confirming that the wettability of these liquid metals is due to the oxide skin.

Qin Xu; Nikolai Qudalov; Qiti Guo; Heinrich Jaeger; Eric Brown

2012-01-23

68

Gallium phosphide energy converters  

NASA Technical Reports Server (NTRS)

Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

1995-01-01

69

Gallium phosphide energy converters  

SciTech Connect

Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp {minus}17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

Sims, P.E.; Dinetta, L.C.; Goetz, M.A.

1995-10-01

70

Gallium phosphide energy converters  

NASA Astrophysics Data System (ADS)

Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

1995-10-01

71

Gallium in cancer treatment.  

PubMed

Gallium (Ga) is the second metal ion, after platinum, to be used in cancer treatment. Its activities are numerous and various. It modifies three-dimensional structure of DNA and inhibits its synthesis, modulates protein synthesis, inhibits the activity of a number of enzymes, such as ATPases, DNA polymerases, ribonucleotide reductase and tyrosine-specific protein phosphatase. Ga alters plasma membrane permeability and mitochondrial functions. Ga salts are taken up more efficiently and more specifically by tumour cells when orally administered. New compounds have been prepared: Ga maltolate, doxorubicin-Ga-transferrin conjugate and Tris(8-quinolinolato)Ga(III), which show interesting activities. Ga toxicity is well documented in vitro and in vivo in animals. In humans, the oral administration Ga is less toxic, and allows a chronic treatment, allowing an improvement of its bioavailability in tumours, by comparison with the parenteral use. The anticancer activity of Ga salts has been demonstrated but other effects have also been noted such as many bone effects that could be useful in bone metastatic patients. Its has also been shown that a long period of administration could induce tumour fibrosis. Ga is synergistic with other anticancer drugs. Although not as potent as platinum in vitro, the anticancer activity of Ga should not be ignored, but the schedule of administration still needs to be optimised and new compounds are now under clinical investigations. PMID:12050020

Collery, Philippe; Keppler, Bernhard; Madoulet, Claudie; Desoize, Bernard

2002-06-01

72

Medical Applications and Toxicities of Gallium Compounds  

PubMed Central

Over the past two to three decades, gallium compounds have gained importance in the fields of medicine and electronics. In clinical medicine, radioactive gallium and stable gallium nitrate are used as diagnostic and therapeutic agents in cancer and disorders of calcium and bone metabolism. In addition, gallium compounds have displayed anti-inflammatory and immunosuppressive activity in animal models of human disease while more recent studies have shown that gallium compounds may function as antimicrobial agents against certain pathogens. In a totally different realm, the chemical properties of gallium arsenide have led to its use in the semiconductor industry. Gallium compounds, whether used medically or in the electronics field, have toxicities. Patients receiving gallium nitrate for the treatment of various diseases may benefit from such therapy, but knowledge of the therapeutic index of this drug is necessary to avoid clinical toxicities. Animals exposed to gallium arsenide display toxicities in certain organ systems suggesting that environmental risks may exist for individuals exposed to this compound in the workplace. Although the arsenic moiety of gallium arsenide appears to be mainly responsible for its pulmonary toxicity, gallium may contribute to some of the detrimental effects in other organs. The use of older and newer gallium compounds in clinical medicine may be advanced by a better understanding of their mechanisms of action, drug resistance, pharmacology, and side-effects. This review will discuss the medical applications of gallium and its mechanisms of action, the newer gallium compounds and future directions for development, and the toxicities of gallium compounds in current use. PMID:20623028

Chitambar, Christopher R.

2010-01-01

73

A FETISH for gallium arsenide  

SciTech Connect

An overview of the development of a new dielectric material, cubic-GaS, from the synthesis of new organometallic compounds to the fabrication of a new class of gallium arsenide based transistor is presented as a representative example of the possibility that inorganic chemistry can directly effect the development of new semiconductor devices. The gallium sulfido compound [({sup t}Bu)GaS]{sub 4}, readily prepared from tri-tert-butyl gallium, may be used as a precursor for the growth of GaS thin films by metal organic chemical vapor deposition (MOCVD). Photoluminescence and electronic measurements indicate that this material provides a passivation coating for GaAs. Furthermore, the insulating properties of cubic-GaS make it suitable as the insulating gate layer in a new class of GaAs transistor: a field effect transistor with a sulfide heterojunction (FETISH).

Barron, A.R. [Rice Univ., Houston, TX (United States)

1996-12-31

74

GALLIUM--1999 29.1 By Deborah A. Kramer  

E-print Network

% of gallium consumed in the United States was in the form of gallium arsenide (GaAs). Analog integratedGALLIUM--1999 29.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared by Carolyn F. Crews, statistical assistant. Gallium demand in the United States was satisfied by imports

75

GALLIUM--2001 29.1 By Deborah A. Kramer  

E-print Network

, a significant consumer of gallium arsenide (GaAs)-based devices. As the gallium demand declined during 2001GALLIUM--2001 29.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared in lower demand for gallium from the record-high levels that transpired in 2000. The largest factor

76

Interaction between copper and gallium  

NASA Astrophysics Data System (ADS)

The interaction between solid copper and liquid gallium is considered, which is the main process during the setting of diffusion-solidifying solders. The dependences of the process rate and the size characteristics on the phase composition of the initial mixture are found. The intermetallic compound CuGa2 is shown to be the product of the interaction in all cases.

Ancharov, A. I.; Grigoryeva, T. F.; Barinova, A. P.; Boldyrev, V. V.

2008-12-01

77

Gallium scan in intracerebral sarcoidosis  

SciTech Connect

Sarcoidosis involving the nervous system probably occurs in about 4% of patients. The usefulness of brain scintigraphy in these cases has been suggested. In this case of cerebral sarcoid granuloma, gallium imaging demonstrated the lesion before treatment and showed disappearance of the lesion after corticosteroid treatment, which correlated with the patient's clinical improvement.

Makhija, M.C.; Anayiotos, C.P.

1981-07-01

78

P-type gallium nitride  

DOEpatents

Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5.times.10.sup.11 /cm.sup.3 and hole mobilities of about 500 cm.sup.2 /V-sec, measured at 250.degree. K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al.

Rubin, Michael (Berkeley, CA); Newman, Nathan (Montara, CA); Fu, Tracy (Berkeley, CA); Ross, Jennifer (Pleasanton, CA); Chan, James (Berkeley, CA)

1997-01-01

79

P-type gallium nitride  

DOEpatents

Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5{times}10{sup 11} /cm{sup 3} and hole mobilities of about 500 cm{sup 2} /V-sec, measured at 250 K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al. 9 figs.

Rubin, M.; Newman, N.; Fu, T.; Ross, J.; Chan, J.

1997-08-12

80

Gallium scintigraphy in acute panniculitis  

SciTech Connect

Gallium scintigraphy was performed in a 27-yr-old female in search of a possible occult focus of infection; it showed an unusual diffuse superficial accumulation in the thighs and buttocks. Biopsy of an area of abnormal uptake showed lobular panniculitis which, in the clinical context, led to the diagnosis of Weber-Christian syndrome.

Choy, D. (Prince of Wales Hospital, Randwick, Australia); Murray, I.P.C.; Ford, J.C.

1981-11-01

81

A study of the applicability of gallium arsenide and silicon carbide as aerospace sensor materials  

NASA Technical Reports Server (NTRS)

Most of the piezoresistive sensors, to date, are made of silicon and germanium. Unfortunately, such materials are severly restricted in high temperature environments. By comparing the effects of temperature on the impurity concentrations and piezoresistive coefficients of silicon, gallium arsenide, and silicon carbide, it is being determined if gallium arsenide and silicon carbide are better suited materials for piezoresistive sensors in high temperature environments. The results show that the melting point for gallium arsenide prevents it from solely being used in high temperature situations, however, when used in the alloy Al(x)Ga(1-x)As, not only the advantage of the wider energy band gas is obtained, but also the higher desire melting temperature. Silicon carbide, with its wide energy band gap and higher melting temperature suggests promise as a high temperature piezoresistive sensor.

Hurley, John S.

1990-01-01

82

Gallium nitride electronics  

NASA Astrophysics Data System (ADS)

In the past two decades, there has been increasing research and industrial activity in the area of gallium nitride (GaN) electronics, stimulated first by the successful demonstration of GaN LEDs. While the promise of wide band gap semiconductors for power electronics was recognized many years before this by one of the contributors to this issue (J Baliga), the success in the area of LEDs acted as a catalyst. It set the field of GaN electronics in motion, and today the technology is improving the performance of several applications including RF cell phone base stations and military radar. GaN could also play a very important role in reducing worldwide energy consumption by enabling high efficiency compact power converters operating at high voltages and lower frequencies. While GaN electronics is a rapidly evolving area with active research worldwide, this special issue provides an opportunity to capture some of the great advances that have been made in the last 15 years. The issue begins with a section on epitaxy and processing, followed by an overview of high-frequency HEMTs, which have been the most commercially successful application of III-nitride electronics to date. This is followed by review and research articles on power-switching transistors, which are currently of great interest to the III-nitride community. A section of this issue is devoted to the reliability of III-nitride devices, an area that is of increasing significance as the research focus has moved from not just high performance but also production-worthiness and long-term usage of these devices. Finally, a group of papers on new and relatively less studied ideas for III-nitride electronics, such as interband tunneling, heterojunction bipolar transistors, and high-temperature electronics is included. These areas point to new areas of research and technological innovation going beyond the state of the art into the future. We hope that the breadth and quality of articles in this issue will make it an excellent reference for newcomers and experienced researchers in this field for several years. We thank Alice Malhador at IOP Publishing for her constant encouragement and guidance in putting together this special issue on GaN electronics.

Rajan, Siddharth; Jena, Debdeep

2013-07-01

83

Gallium Arsenide Integrated Circuits 1988 ANZAAS Congress, VLSI Section  

E-print Network

Gallium Arsenide Integrated Circuits 1988 ANZAAS Congress, VLSI Section Anthony E. Parker are collaborating to establish a local GaAs digital integrated design and fabrication capability. Gallium Arsenide Laboratory for Communication Science and Engineering, Sydney University Electrical Engineering Gallium

84

In vitro bio-functionality of gallium nitride sensors for radiation biophysics.  

PubMed

There is an increasing interest in the integration of hybrid bio-semiconductor systems for the non-invasive evaluation of physiological parameters. High quality gallium nitride and its alloys show promising characteristics to monitor cellular parameters. Nevertheless, such applications not only request appropriate sensing capabilities but also the biocompatibility and especially the biofunctionality of materials. Here we show extensive biocompatibility studies of gallium nitride and, for the first time, a biofunctionality assay using ionizing radiation. Analytical sensor devices are used in medical settings, as well as for cell- and tissue engineering. Within these fields, semiconductor devices have increasingly been applied for online biosensing on a cellular and tissue level. Integration of advanced materials such as gallium nitride into these systems has the potential to increase the range of applicability for a multitude of test devices and greatly enhance sensitivity and functionality. However, for such applications it is necessary to optimize cell-surface interactions and to verify the biocompatibility of the semiconductor. In this work, we present studies of mouse fibroblast cell activity grown on gallium nitride surfaces after applying external noxa. Cell-semiconductor hybrids were irradiated with X-rays at air kerma doses up to 250 mGy and the DNA repair dynamics, cell proliferation, and cell growth dynamics of adherent cells were compared to control samples. The impact of ionizing radiation on DNA, along with the associated cellular repair mechanisms, is well characterized and serves as a reference tool for evaluation of substrate effects. The results indicate that gallium nitride does not require specific surface treatments to ensure biocompatibility and suggest that cell signaling is not affected by micro-environmental alterations arising from gallium nitride-cell interactions. The observation that gallium nitride provides no bio-functional influence on the cellular environment confirms that this material is well suited for future biosensing applications without the need for additional chemical surface modification. PMID:22771805

Hofstetter, Markus; Howgate, John; Schmid, Martin; Schoell, Sebastian; Sachsenhauser, Matthias; Adigüzel, Denis; Stutzmann, Martin; Sharp, Ian D; Thalhammer, Stefan

2012-07-27

85

GALLIUM--2000 30.1 By Deborah A. Kramer  

E-print Network

in the United States was in the form of gallium arsenide (GaAs). Analog integrated circuits (ICs) wereGALLIUM--2000 30.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared by Carolyn F. Crews, statistical assistant. By yearend, worldwide gallium supplies were insufficient to meet

86

Large grain gallium arsenide thin films  

SciTech Connect

Polycrystalline gallium arsenide films deposited on tungsten/graphite substrates have been used for the fabrication of thin film solar cells. Gallium arsenide films deposited on foreign substrates of 10 ..mu..m or less thickness exhibit, in most cases, pronounced shunting effects due to grain boundaries. MOS solar cells of 9 cm/sup 2/ area with an AMI efficiency of 8.5% and p/sup +//n/n/sup +/ homojunction solar cells of 1 cm/sup 2/ area with an AM1 efficiency of 8.8% have been prepared. However, in order to further improve the conversion efficiency before the development of effective passivation techniques, gallium arsenide films with large and uniform grain structure are necessary. The large grain gallium arsenide films have been prepared by using the arsine treatment of a thin layer of molten gallium on the substrate surface and the recrystallized germanium films on tungsten/graphite as substrates.

Chu, S.S.; Chen, W.J.; Chu, T.L.; Firouzi, H.; Han, Y.X.; Wang, Q.H.

1984-05-01

87

Gallium Electromagnetic (GEM) Thrustor Concept and Design  

NASA Technical Reports Server (NTRS)

We describe the design of a new type of two-stage pulsed electromagnetic accelerator, the gallium electromagnetic (GEM) thruster. A schematic illustration of the GEM thruster concept is given in Fig. 1. In this concept, liquid gallium propellant is pumped into the first stage through a porous metal electrode using an electromagneticpump[l]. At a designated time, a pulsed discharge (approx.10-50 J) is initiated in the first stage, ablating the liquid gallium from the porous electrode surface and ejecting a dense thermal gallium plasma into the second state. The presence of the gallium plasma in the second stage serves to trigger the high-energy (approx.500 I), send-stage puke which provides the primary electromagnetic (j x B) acceleration.

Polzin, Kurt A.; Markusic, Thomas E.

2006-01-01

88

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2007. One company in Utah  

E-print Network

$11 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about Relations 12-31-07 Gallium arsenide wafers, undoped 2853.00.0010 2.8% ad val. Gallium arsenide wafers, doped64 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production

89

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2009. One company in Utah  

E-print Network

$14 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about Relations 12-31-09 Gallium arsenide wafers, undoped 2853.00.0010 2.8% ad val. Gallium arsenide wafers, doped58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production

90

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2012. One company in Utah  

E-print Network

.S. gallium consumption, were valued at about $32 million. Gallium arsenide (GaAs) and gallium nitride (Ga Number Normal Trade Relations 12­31­12 Gallium arsenide wafers, undoped 2853.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Gallium metal 8112.92.1000 3.0% ad val. Depletion Allowance

91

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2008. One company in Utah  

E-print Network

$23 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about Relations 12-31-08 Gallium arsenide wafers, undoped 2853.00.0010 2.8% ad val. Gallium arsenide wafers, doped60 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production

92

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2004. One company in Utah  

E-print Network

$4 million, most of which was low-purity material. Gallium arsenide (GaAs) and gallium nitride (Ga. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 381864 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production

93

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1999. Two companies in  

E-print Network

of U.S. gallium consumption, were valued at about $11.2 million. Gallium arsenide (GaAs) components.91.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers66 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production

94

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary (crude, unrefined) gallium was recovered in 2013. Globally,  

E-print Network

.S. gallium consumption, were valued at about $16 million. Gallium arsenide (GaAs) and gallium nitride (Ga arsenide wafers, undoped 2853.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free58 GALLIUM (Data in kilograms of gallium content unless otherwise noted) Domestic Production

95

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1996. Two companies in  

E-print Network

of U.S. gallium consumption, were valued at about $7.9 million. Gallium arsenide (GaAs) components. 25.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. 25.0% ad val. Gallium62 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production

96

Clinical applications of Gallium-68.  

PubMed

Gallium-68 is a positron-emitting radioisotope that is produced from a (68)Ge/(68)Ga generator. As such it is conveniently used, decoupling radiopharmacies from the need for a cyclotron on site. Gallium-68-labeled peptides have been recognized as a new class of radiopharmaceuticals showing fast target localization and blood clearance. (68)Ga-DOTATOC, (8)Ga-DOTATATE, (68)Ga-DOTANOC, are the most prominent radiopharmaceuticals currently in use for imaging and differentiating lesions of various somatostatin receptor subtypes, overexpressed in many neuroendocrine tumors. There has been a tremendous increase in the number of clinical studies with (68)Ga over the past few years around the world, including within the United States. An estimated ?10,000 scans are being performed yearly in Europe at about 100 centers utilizing (68)Ga-labeled somatostatin analogs within clinical trials. Two academic sites within the US have also begun to undertake human studies. This review will focus on the clinical experience of selected, well-established and recently applied (68)Ga-labeled imaging agents used in nuclear medicine. PMID:23522791

Banerjee, Sangeeta Ray; Pomper, Martin G

2013-06-01

97

Clinical Applications of Gallium-68  

PubMed Central

Gallium-68 is a positron-emitting radioisotope that is produced from a 68Ge/68Ga generator. As such it is conveniently used, decoupling radiopharmacies from the need for a cyclotron on site. Gallium-68-labeled peptides have been recognized as a new class of radiopharmaceuticals showing fast target localization and blood clearance. 68Ga-DOTATOC, 8Ga-DOTATATE, 68Ga-DOTANOC, are the most prominent radiopharmaceuticals currently in use for imaging and differentiating lesions of various somatostatin receptor subtypes, overexpressed in many neuroendocrine tumors. There has been a tremendous increase in the number of clinical studies with 68Ga over the past few years around the world, including within the United States. An estimated ~10,000 scans are being performed yearly in Europe at about 100 centers utilizing 68Ga-labeled somatostatin analogs within clinical trials. Two academic sites within the US have also begun to undertake human studies. This review will focus on the clinical experience of selected, well-established and recently applied 68Ga-labeled imaging agents used in nuclear medicine. PMID:23522791

Banerjee, Sangeeta Ray; Pomper, Martin G.

2013-01-01

98

The Soviet American Gallium Experiment (SAGE)  

SciTech Connect

A radiochemical experiment using the reaction v/sub e/ = /sup 71/Ga + e/sup e/ to determine the integral flux of low-energy neutrinos from the sun is currently under preparation at the Baksan Neutrino Observatory in the USSR. Measurements are scheduled to commence by late 1988 using /approximately/30 tonnes of metallic gallium. With this amount of gallium it should be possible to obtain a fractional statistical accuracy of 12 to 15% after one year (assuming the standard solar model neutrino flux). While initial measurements are in progress, installation of the remaining 30 tonnes of gallium will proceed in order to perform the full 60 tonne experiment.

Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.P.; Avdeyev, A.V.; Belousko, Yu.I.; Bychuk, O.V.; Danshin, S.N.; Eroshkina, L.A.; Faizov, E.L.; Gayevsky, V.I.; Gavrin, V.N.; Grigorjev, A.M.; Kalikhov, A.V.; Kireyev, S.M.; Knodel, T.V.; Knyshenko, I.I.; Kornoukhov, V.N.; Mezentsevah, S.A.; Mirnov, I.N.; Ejikbosverpdze, Sh.M.; Ostrinsky, A.V.; Petukhov, V.V.; Pikhulya, O.E.; Pshukov, A.M.; Revzin, N.Ye.; Shikhin, A.A.; Shilo, Yu.I.; Slyusareva, Ye.D.; Strepanyuk, M.V.; Tikhonov, A.A.; Timofeyev, P.V.; Veretenkin, E.P.; Vermul, V.M.; Yants, V.E.; Zakhorov, Yu.I.; Zatsepin, G.T.; Cleveland, B.C.; Bowles, T.J.; Elliott, S.R.; O'Brien, H.A.; Wark, D.L.; Wilkerson, J.F.; Cherry, M.L.; Kouzes, R.T.

1988-01-01

99

Gallium-67 activity in bronchoalveolar lavage fluid in sarcoidosis  

SciTech Connect

Roentgenograms and gallium-67 scans and gallium-67 counts of BAL fluid samples, together with differential cell counts, have proved to be useful in assessing activity and lung involvement in sarcoidosis. In active pulmonary sarcoidosis gallium-67 scans are usually positive. Quantitation of gallium-67 uptake in lung scans, however, may be difficult. Because gallium-67 uptake and cell counts in BAL fluid may be correlated, we set out to investigate gallium-67 activity in BAL fluid recovered from patient of different groups. Sixteen patients with recently diagnosed and untreated sarcoidosis, nine patients with healthy lungs, and five patients with CFA were studied. Gallium-67 uptake of the lung, gallium-67 activity in the lavage fluid, SACE and LACE levels, and alpha 1-AT activity were measured. Significantly more gallium-67 activity was found in BAL fluid from sarcoidosis patients than in that from CFA patients (alpha = .001) or patients with healthy lungs (alpha = .001). Gallium-67 activity in BAL fluid could be well correlated with the number of lymphocytes in BAL fluid, but poorly with the number of macrophages. Subjects with increased levels of SACE or serum alpha 1-AT showed higher lavage gallium-67 activity than did normals, but no correlation could be established. High gallium-67 activity in lavage fluid may be correlated with acute sarcoidosis or physiological deterioration; low activity denotes change for the better. The results show that gallium-67 counts in BAL fluid reflects the intensity of gallium-67 uptake and thus of activity of pulmonary sarcoidosis.

Trauth, H.A.; Heimes, K.; Schubotz, R.; von Wichert, P.

1986-01-01

100

Recovery of gallium from aluminum industry residues  

SciTech Connect

A procedure is proposed to recover gallium from flue dust aluminum residues produced in plants by using solid-phase extraction with a commercial polyether-type polyurethane foam (PUF). Gallium can be separated from high concentrations of aluminum, iron, nickel, titanium, vanadium, copper, zinc, sulfate, fluoride, and chloride by extraction with PUF from 3 M sulfuric acid and 3 M sodium chloride concentration medium with at least a 92% efficiency. Gallium backextraction was fast and quantitative with ethanol solution. In all recovery steps commercial-grade reagents could be used, including tap water. The recovered gallium was precipitated with sodium hydroxide solution, purified by dissolution and precipitation, calcinated, and the final oxide was 98.6% pure.

Carvalho, M.S.; Neto, K.C.M.; Nobrega, A.W.; Medeiros, J.A.

2000-01-01

101

Radiochemical separation of gallium by amalgam exchange  

USGS Publications Warehouse

An amalgam-exchange separation of radioactive gallium from a number of interfering radioisotopes has been developed. A dilute (ca. 0.3%) gallium amalgam is agitated with a slightly acidic solution of 72Ga3+ containing concentrations of sodium thiocyanate and either perchlorate or chloride. The amalgam is then removed and the radioactive gallium stripped by agitation with dilute nitric acid. The combined exchange yield of the perchlorate-thiocyanate system is 90??4% and that of the chloride-thiocyanate system is 75??4%. Decontamination yields of most of the 11 interfering isotopes studied were less than 0.02%. The technique is applicable for use with activation analysis for the determination of trace amounts of gallium. ?? 1969.

Ruch, R. R.

1969-01-01

102

Development of gallium arsenide solar cells  

NASA Technical Reports Server (NTRS)

The potential of ion implantation as a means of developing gallium arsenide solar cells with high efficiency performance was investigated. Computer calculations on gallium arsenide cell characteristics are presented to show the effects of surface recombination, junction space-charge recombination, and built-in fields produced by nonuniform doping of the surface region. The fabrication technology is summarized. Electrical and optical measurements on samples of solar cells are included.

1973-01-01

103

The solubility of hydrogen and deuterium in alloyed, unalloyed and impure plutonium metal  

SciTech Connect

Pressure-Composition-Temperature (PCT) data are presented for the plutonium-hydrogen (Pu-H) and plutonium-deuterium (Pu-D) systems in the solubility region up to terminal solubility (precipitation of PuH{sub 2}). The heats of solution for PuH{sub s} and PuD{sub s} are determined from PCT data in the ranges 350-625 C for gallium alloyed Pu and 400-575 C for unalloyed Pu. The solubility of high purity plutonium alloyed with 2 at.% gallium is compared to high purity unalloyed plutonium. Significant differences are found in hydrogen solubility for unalloyed Pu versus gallium alloyed Pu. Differences in hydrogen solubility due to an apparent phase change are observable in the alloyed and unalloyed solubilities. The effect of iron impurities on Pu-Ga alloyed Pu is shown via hydrogen solubility data as preventing complete homogenization.

Richmond, Scott [Los Alamos National Laboratory; Bridgewater, Jon S [Los Alamos National Laboratory; Ward, John W [Los Alamos National Laboratory; Allen, Thomas A [Los Alamos National Laboratory

2009-01-01

104

Potential of gallium-based leads for cardiac rhythm management devices.  

PubMed

We propose the use of gallium (Ga), a metal that is liquid at physiological temperatures, or one of its alloys, for use as the conducting material in the leads of implantable pacemakers or cardioverter defibrillators. It is proposed that a liquid conductor will make these leads more pliable and thus less susceptible to fracture in situ. As an initial step towards utilizing liquid gallium in leads, the biocompatibility of Ga was investigated via cytotoxicity, hemocompatibility, and intracutaneous injection testing. Unipolar pacing Ga prototypes were fabricated by adapting existing pacemaker leads. The electrical impedance and pulse transmission ability of these leads were examined. Ga was well tolerated both in vitro and in vivo. Additionally, the Ga prototypes conductors behaved as low magnitude resistances that did not distort pulses as generated by conventional pacemakers. These results indicate that Ga is an appropriate material for implantable cardiac stimulators and will be a focus of our liquid metal prototypes. PMID:22254318

Kyle, Aaron M; Leahy-Glass, Nichole; Combs, William; March, Keith L

2011-01-01

105

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2002. Two companies in  

E-print Network

. Gallium arsenide (GaAs) components represented about 98% of domestic gallium consumption. About 34 arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free66 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production

106

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2003. One company in  

E-print Network

$4 million, most of which was low-purity material. Gallium arsenide (GaAs) and gallium nitride (Ga Relations 12/31/03 Gallium metal 8112.92.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Depletion Allowance: Not applicable

107

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2001. Two companies in  

E-print Network

of U.S. gallium consumption, were valued at about $29 million. Gallium arsenide (GaAs) components Relations 12/31/01 Gallium metal 8112.91.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Depletion Allowance: Not applicable

108

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2005. One company in Utah  

E-print Network

$4 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented about Relations 12-31-05 Gallium metal 8112.92.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Depletion Allowance: Not applicable

109

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1997. Two companies in  

E-print Network

of U.S. gallium consumption, were valued at about $7.0 million. Gallium arsenide (GaAs) components arsenide wafers, undoped 2851.00.0010 2.8% ad val. 25.0% ad val. Gallium arsenide wafers, doped 381862 GALLIUM (Data in kilograms of gallium content, unless otherwise noted) Domestic Production

110

(Data in kilograms of gallium content, unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2000. Two companies in  

E-print Network

of U.S. gallium consumption, were valued at about $15 million. Gallium arsenide (GaAs) components Relations 12/31/00 Gallium metal 8112.91.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Depletion Allowance: Not applicable

111

(Data in kilograms of gallium content unless otherwise noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 2006. One company in Utah  

E-print Network

$5.5 million. Gallium arsenide (GaAs) and gallium nitride (GaN) electronic components represented Relations 12-31-06 Gallium metal 8112.92.1000 3.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free. Depletion Allowance: Not applicable

112

Window structure for passivating solar cells based on gallium arsenide  

NASA Technical Reports Server (NTRS)

Passivated gallium arsenide solar photovoltaic cells with high resistance to moisture and oxygen are provided by means of a gallium arsenide phosphide window graded through its thickness from arsenic rich to phosphorus rich.

Barnett, Allen M. (Inventor)

1985-01-01

113

Window structure for passivating solar cells based on gallium arsenide  

SciTech Connect

Passivated gallium arsenide solar photovoltaic cells with high resistance to moisture and oxygen are provided by means of a gallium arsenide phosphide window graded through its thickness from arsenic rich to phosphorus rich.

Barnett, A. M.

1985-10-01

114

INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS A Dissertation  

E-print Network

1 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS A Dissertation Submitted to the Graduate;2 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS Abstract by Sajid Kabeer In0.53Ga0.47As tunnel-type dopant, exhibited a backward diode behavior. #12;4 INDIUM-GALLIUM-ARSENIDE AND GERMANIUM TUNNEL JUNCTIONS

115

GALLIUM--1998 29.1 By Deborah A. Kramer  

E-print Network

consumed in the United States was in the form of gallium arsenide (GaAs). Analog integrated circuits (ICGALLIUM--1998 29.1 GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared by Carolyn F. Crews, statistical assistant. Gallium demand in the United States was satisfied by imports

116

Photoelectron energy distribution and spin polarization from activated gallium arsenide  

E-print Network

L-1027 Photoelectron energy distribution and spin polarization from activated gallium arsenide H.90 1. Introduction. It has been shown [1-4] that a p-type gallium arsenide crystal activated ont été effectuées sur des photoélectrons émis par un cristal d'arséniure de gallium activé. Les

Paris-Sud XI, Université de

117

Effects of titanium-dental restorative alloy galvanic couples on cultured cells.  

PubMed

The potential exists for titanium and amalgams to become galvanically coupled in the oral cavity. While low galvanic corrosion rates have been measured in vivo for titanium-amalgam or mercury-free alloy couples, concerns exist over released corrosion products and adverse tissue responses. It was hypothesized in this study that coupling titanium to amalgams or gallium alloys increased the release of metallic corrosion products and decreased cellular activity and function. The effects of titanium coupled and uncoupled to a conventional amalgam, palladium-enriched spherical high copper amalgam, a dispersed type high copper amalgam, and a mercury-free gallium alloy were evaluated in 24-h cell culture tests. Viability, proliferation, and collagen synthesis were evaluated by the uptake of neutral red, 3H-thymidine, and immunoassay of procollagen, respectively, and compared to cells not exposed to any test material. The gallium alloy-titanium couple resulted in significant decreases in cellular viability, proliferation, and collagen synthesis as compared to the other coupled and uncoupled samples. Few differences in the cellular responses of the other coupled and uncoupled samples were observed. Atomic absorption analyses indicated increased release of metal ions from the amalgam and gallium alloy samples coupled to titanium as compared to their uncoupled condition, although the differences were not always significant. Galvanic corrosion of amalgam-titanium couples in the long term may become significant, and further research is needed. Coupling the gallium alloy to titanium may result in increased galvanic corrosion and cytotoxic responses. PMID:9619437

Bumgardner, J D; Johansson, B I

1998-01-01

118

[Gallium-67 scintigraphy in malignant lymphoma].  

PubMed

The presence of a residual mass is a frequent and difficult problem in the treatment of Hodgkin's or non-Hodgkin's lymphoma: since it is of major importance to determine whether the lesion is a fibrous mass or a still progressing tumour requiring additional therapy. Gallium-67 scanning, performed in a series of 52 patients, provides an answer to this question since there is an excellent correlation between gallium uptake by the tumoral masses and their progressiveness. Magnetic resonance imaging was carried out in half of our patients: the finding of a low-intensity signal on T2-weighted sequences proved that the residual mass was fibrous, whereas a high-intensity signal on T2-weighted sequences did not distinguish between fibrous and tumour masses. The priceless information provided by the simple and non invasive method that is gallium scanning is extremely useful to evaluate the extension of lymphomas and to determine whether residual masses are tumoral or fibrous. PMID:8511078

Cohen-Haguenauer, O; Brice, P; Gaci, M; Le Pailleur, A; Cheval, E; Bris, C; Frija, J; Gisselbrecht, C; Rain, J D; Najean, Y

1993-03-27

119

/sup 67/Gallium lung scans in progressive systemic sclerosis  

SciTech Connect

/sup 67/Gallium lung scans were performed in 19 patients with progressive systemic sclerosis (scleroderma). Results were expressed quantitatively as the /sup 67/Gallium Uptake Index. The mean total pulmonary /sup 67/Gallium Uptake Index in patients was significantly higher than that in controls (41 versus 25), and 4 patients (21%) fell outside the normal range. There were no clinical or laboratory variables that correlated with the /sup 56/Gallium uptake. Increased pulmonary /sup 67/Gallium uptake in scleroderma may prove useful as an index of pulmonary disease activity.

Baron, M.; Feiglin, D.; Hyland, R.; Urowitz, M.B.; Shiff, B.

1983-08-01

120

Design and modeling of a single-crystal iron-gallium large magnetostrictive dynamic research transducer  

NASA Astrophysics Data System (ADS)

Alloys of iron and non-magnetic gallium (of the form Fe1-xGax where x ranges from 13 to 30) exhibit large magnetostrictions of over 300 ppm at room temperature that are produced by saturation magnetic fields of approximately 600 Oe. While not producing magnetostrictions of the degree achievable with giant magnetostrictives, large magnetostrictive alloys of iron and gallium, called Galfenol, have much more desirable mechanical characteristics, such as non-brittleness and in-plane auxetic behavior. Additionally, Galfenol requires a much smaller saturation magnetic field than the giant magnetostrictives Terfenol and Terfenol-D (alloys of Iron and non-metallic Terbium and Dysprosium). Beginning from the body of knowledge gained from Terfenol and Terfenol-D dynamic research transducer designs is a good starting point for designing a Galfenol dynamic research transducer. However, several modifications are being made to adapt the transducer to some of Galfenol's unique properties. Any measured value uncertainty will quickly propagate through the calculated material properties. While not completely successful at addressing all the unique aspects Galfenol in this transducer design, the data presented will assist in future design attempts.

Twarek, Luke M.; Haack, Sarah J.; Flatau, Alison B.

2004-07-01

121

Radiation damage of gallium arsenide production cells  

NASA Technical Reports Server (NTRS)

High efficiency liquid phase epitaxy (LPE) gallium arsenide cells were irradiated with 1 Mev electrons up to fluences of 1 times 10 to the 16th power cm-2. Measurements of spectral response and dark and illuminated I-V data were made at each fluence and then, using computer codes, the experimental data was fitted to gallium arsenide cell models. In this way it was possible to determine the extent of the damage, and hence damage coefficients in both the emitter and base of the cell.

Mardesich, N.; Joslin, D.; Garlick, J.; Lillington, D.; Gillanders, M.; Cavicchi, B.; Scott-Monck, J.; Kachare, R.; Anspaugh, B.

1987-01-01

122

Four Terminal Gallium Nitride MOSFETs  

NASA Astrophysics Data System (ADS)

All reported gallium nitride (GaN) transistors to date have been three-terminal devices with source, drain, and gate electrodes. In the case of GaN MOSFETs, this leaves the bulk of the device at a floating potential which can impact device threshold voltage. In more traditional silicon-based MOSFET fabrication a bulk contact can be made on the back side of the silicon wafer. For GaN grown on sapphire substrates, however, this is not possible and an alternate, front-side bulk contact must be investigated. GaN is a III-V, wide band gap semiconductor that as promising material parameters for use in high frequency and high power applications. Possible applications are in the 1 to 10 GHz frequency band and power inverters for next generation grid solid state transformers and inverters. GaN has seen significant academic and commercial research for use in Heterojunction Field Effect Transistors (HFETs). These devices however are depletion-mode, meaning the device is considered "on" at zero gate bias. A MOSFET structure allows for enhancement mode operation, which is normally off. This mode is preferrable in high power applications as the device has lower off-state power consumption and is easier to implement in circuits. Proper surface passivation of seminconductor surface interface states is an important processing step for any device. Preliminary research on surface treatments using GaN wet etches and depletion-mode GaN devices utilizing this process are discussed. Devices pretreated with potassium pursulfate prior to gate dielectric deposition show significant device improvements. This process can be applied to any current GaN FET. Enhancement-mode GaN MOSFETs were fabricated on magnesium doped p-type Wurtzite gallium nitride grown by Metal Organic Chemical Vapor Deposition (MOCVD) on c-plane sapphire substrates. Devices utilized ion implant source and drain which was activated under NH3 overpressure in MOCVD. Also, devices were fabricated with a SiO2 gate dielectric and metal gate. Preliminary devices exhibited high GaN-oxide interface state density, Dit, on the order of 1013 cm-2· eV-1. Additional experiments and device fabrication was focused on improving device performance through optimization of the ion implantation activation anneal as well as incorporation of a bulk p-type ohmic contact and migration to a thicker, lower defect density, HVPE-grown template substrate. The first reported MOSFET on HVPE grown GaN substrates (templates) is reported with peak measured drain current of 1.05 mA/mm and a normalized transconductance of 57 muS/mm. Fabricated devices exhibited large (greater than 1 muA) source-to-drain junction leakage which is attributed to low activated doping density in the MOCVD-grown p-type bulk. MOSFETs fabricated on template substrates show more than twice the measured drain current as similar devices fabricated on traditional MOCVD GaN on sapphire substrates for the same bias conditions. Also, template MOSFETs have decreased gate leakage which allowed for a much greater range of operation. This performance increase is attributed to a more than doubled effective channel mobility on template GaN MOSFETs due to decreased crystal defect scattering when compared to a MOCVD-grown GaN-on-sapphire MOSFET. Fabricated MOSFETs also exhibit decreased interface state density with lower bound of 2.2x1011 cm-2·eV-1 when compared to prelimary MOSFETs. This decrease is associated with the use of a sacrificial oxide cap during source/drain activation. Suggested work for continued research is also presented which includes experiments to improve source/drain ion implantation profile, utilization of selective area growth for the active area, improved n- and p-type ohmic contact resistance and investigation of alternate oxides.

Veety, Matthew Thomas

123

Atomistic modeling of thermodynamic properties of Pu-Ga alloys based on the Invar mechanism  

NASA Astrophysics Data System (ADS)

We present an atomistic model that accounts for a range of anomalous thermodynamic properties of the fcc ? phase of Pu-Ga alloys in terms of the Invar mechanism. Two modified embedded atom method potentials are employed to represent competing electronic states in ?-Pu, each of which has an individual configuration dependence as well as distinct interactions with gallium. Using classical Monte Carlo simulations, we compute the temperature dependence of various thermodynamic properties for different dilute gallium concentrations. The model reproduces the observed effects of excessive volume reduction along with a rapid shift in thermal expansion from negative to positive values with increasing gallium concentration. It also predicts progressive stiffening upon dilute-gallium alloying, while the calculated thermal softening is nearly independent of the gallium concentration in agreement with resonant ultrasound spectroscopy measurements in the literature. Analysis of the local structure predicted by the model indicates that the distribution of the gallium atoms is not completely random in the ? phase due to the presence of short-range order associated with the Invar mechanism. This effect is consistent with the nanoscale heterogeneity in local gallium concentration which is observed in recent extended x-ray absorption fine structure spectroscopy experiments. Implications of the Invar effect for phase stability and physical interpretations of the two states are also discussed.

Lee, Tongsik; Taylor, Christopher D.; Lawson, A. C.; Conradson, Steven D.; Chen, Shao Ping; Caro, A.; Valone, Steven M.; Baskes, Michael I.

2014-05-01

124

Gallium Electromagnetic (GEM) Thruster Performance Measurements  

NASA Technical Reports Server (NTRS)

Discharge current, terminal voltage, and mass bit measurements are performed on a coaxial gallium electromagnetic thruster at discharge currents in the range of 7-23 kA. It is found that the mass bit varies quadratically with the discharge current which yields a constant exhaust velocity of 20 km/s. Increasing the electrode radius ratio of the thruster from to 2.6 to 3.4 increases the thruster efficiency from 21% to 30%. When operating with a central gallium anode, macroparticles are ejected at all energy levels tested. A central gallium cathode ejects macroparticles when the current density exceeds 3.7 10(exp 8) A/square m . A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma. The spectra show that neutral, singly, and doubly ionized gallium species are present in the discharge, as well as annular electrode species at higher energy levels. Axial Langmuir triple probe measurements yield electron temperatures in the range of 0.8-3.8 eV and electron densities in the range of 8 x 10(exp )20 to 1.6 x 10(exp 21) m(exp -3) . Triple probe measurements suggest an exhaust plume with a divergence angle of 9 , and a completely doubly ionized plasma at the ablating thruster cathode.

Thomas, Robert E.; Burton, Rodney L.; Polzin, K. A.

2009-01-01

125

A Gallium Multiphase Equation of State  

Microsoft Academic Search

A new SESAME multiphase gallium equation of state (EOS) has been developed. The equation of state includes two of the solid phases (Ga I, Ga III) and a fluid phase. The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We will also explore refreezing via isentropic release and compression.

Scott D Crockett; Carl Greeff

2009-01-01

126

a Gallium Multiphase Equation of State  

Microsoft Academic Search

A new SESAME multiphase Gallium equation of state (EOS) has been developed. It includes three of the solid phases (Ga I, Ga II, Ga III) and a fluid phase (liquid\\/gas). The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We also explore the possibility of re-freezing via dynamic means such as

Scott D. Crockett; Carl W. Greeff

2009-01-01

127

A GALLIUM MULTIPHASE EQUATION OF STATE  

Microsoft Academic Search

A new SESAME multiphase Gallium equation of state (EOS) has been developed. It includes three of the solid phases (Ga I, Ga II, Ga III) and a fluid phase (liquid?gas). The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We also explore the possibility of re-freezing via dynamic means such as

Scott D. Crockett; Carl W. Greeff

2009-01-01

128

A Gallium Multiphase Equation of State  

NASA Astrophysics Data System (ADS)

A new SESAME multiphase gallium equation of state (EOS) has been developed. The equation of state includes two of the solid phases (Ga I, Ga III) and a fluid phase. The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We will also explore refreezing via isentropic release and compression.

Crockett, Scott; Greeff, Carl

2009-06-01

129

Extrapulmonary localization of gallium in sarcoidosis  

SciTech Connect

This paper describes the spectrum of extrapulmonary localization of gallium in patients with sarcoidosis. The usefulness of Ga-67 scintiscans in detecting clinically occult lesions, in directing clinicians to accessible sites for biopsy, and in following the course of extrapulmonary sites of involvement with therapy is emphasized.

Rohatgi, P.K.; Singh, R.; Vieras, F.

1987-01-01

130

Photochromism of doped terbium gallium garnet  

Microsoft Academic Search

In order to understand the photochromic effect in terbium gallium garnet doubly doped with calcium and cerium, the spectral characteristics of absorption changes induced by heating and irradiation are studied. Based on the findings we conclude that the photochromic band at 420nm originates from defects involving Tb4+ . Previously the band was attributed to Ce3+ . Two possible models are

H. Dachraoui; R. A. Rupp; K. Lengyel; M. A. Ellabban; M. Fally; G. Corradi; L. Kovács; L. Ackermann

2006-01-01

131

The photorefractive effect in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

A photorefractive effect in terbium gallium garnet with refractive index changes up to ?n = 5 × 10 -8 for elementary volume phase holograms is reported. The light-induced refractive index changes can directly be attributed via Kramers-Kronig relations to the observed photochromic and light-induced, linear dichroitic behavior. This can also explain the possibility of writing holograms with orthogonally polarized beams.

Sugg, B.; Nürge, H.; Faust, B.; Ruža, E.; Niehüser, R.; Reyher, H.-J.; Rupp, R. A.; Ackermann, L.

1995-01-01

132

Anisotropy of the magnetic susceptibility of gallium  

USGS Publications Warehouse

The bulk magnetic susceptibilities of single gallium crystals and polycrystalline gallium spheres were measured at 25??C. The following anisotropic diamagnetic susceptibilities were found: a axis (-0.119??0. 001)??10-6 emu/g, b axis (-0.416??0.002)??10 -6 emu/g, and c axis (-0.229??0.001) emu/g. The susceptibility of the polycrystalline spheres, assumed to be the average value for the bulk susceptibility of gallium, was (-0.257??0.003)??10-6 emu/g at 25??C, and (-0.299??0.003)??10-6 emu/g at -196??C. The susceptibility of liquid gallium was (0.0031??0.001) ??10-6 emu/g at 30??C and 100??C. Rotational diagrams of the susceptibilities in the three orthogonal planes of the unit cell were not sinusoidal. The anisotropy in the single crystals was presumably caused by the partial overlap of Brillouin zone boundaries by the Fermi-energy surface. The large change in susceptibility associated with the change in state was attributed to the absence of effective mass influence in the liquid state. ?? 1960 The American Institute of Physics.

Pankey, T., Jr.

1960-01-01

133

Thermodynamic binding constants for gallium transferrin  

SciTech Connect

Gallium-67 is widely used as an imaging agent for tumors and inflammatory abscesses. It is well stablished that Ga/sup 3 +/ travels through the circulatory system bound to the serum iron transport protein transferrin and that this protein binding is an essential step in tumor localization. However, there have been conflicting reports on the magnitude of the gallium-transferrin binding constants. Therefore, thermodynamic binding constants for gallium complexation at the two specific metal binding sites of human serum transferrin at pH 7.4 and 5 mM NaHCO/sub 3/ have been determined by UV difference spectroscopy. The conditional constants calculated for 27 mM NaHCO/sub 3/ are log K/sub 1/* = 20.3 and log K/sub 2/* = 19.3. These results are discussed in relation to the thermodynamics of transferrin binding of Fe/sup 3 +/ and to previous reports on gallium binding. The strength of transferrin complexation is also compared to that of a series of low molecular weight ligands by using calculated pM values (pM = -log (Ga(H/sub 2/O)/sub 6/)) to express the effective binding strength at pH 7.4.

Harris, W.R.; Pecoraro, V.L.

1983-01-18

134

Gallium 67 scintigraphy in glomerular disease  

SciTech Connect

To evaluate the diagnostic usefulness of gallium 67 scintigraphy in glomerular disease, 45 patients with various glomerulopathies, excluding lupus nephritis and renal vasculitis, were studied. Persistent renal visualization 48 hours after the gallium injection, a positive scintigram, was graded as + (less than), ++ (equal to), and +++ (greater than) the hepatic uptake. Positive scintigrams were seen in ten of 16 cases of focal segmental glomerulosclerosis, six of 11 cases of proliferative glomerulonephritis, and one case of minimal change, and one of two cases of membranous nephropathy; also in three of six cases of sickle glomerulopathy, two cases of diabetic neuropathy, one of two cases of amyloidosis, and one case of mild chronic allograft rejection. The 25 patients with positive scans were younger than the 20 with negative scans (31 +/- 12 v 42 +/- 17 years; P less than 0.01), and exhibited greater proteinuria (8.19 +/- 7.96 v 2.9 +/- 2.3 S/d; P less than 0.01) and lower serum creatinine values (2 +/- 2 v 4.1 +/- 2.8 mg/dL; P less than 0.01). The amount of proteinuria correlated directly with the intensity grade of the gallium image (P less than 0.02), but there was no correlation between the biopsy diagnosis and the outcome of the gallium scan. It was concluded that gallium scintigraphy is not useful in the differential diagnosis of the glomerular diseases under discussion. Younger patients with good renal function and heavy proteinuria are likely to have a positive renal scintigram regardless of the underlying glomerulopathy.

Bakir, A.A.; Lopez-Majano, V.; Levy, P.S.; Rhee, H.L.; Dunea, G.

1988-12-01

135

Gallium nitride ultraviolet optical modulators  

NASA Astrophysics Data System (ADS)

In narrower band gap semiconductors researchers have exploited the ability to manipulate the exciton resonance via the Quantum Confined Stark Effect to make a variety of different types of optical modulators at infrared wavelengths. In this thesis, the large exciton binding energy of Gallium Nitride is used as the basis for ultraviolet optical modulators without the need for quantum confinement. A 5 x 5 array of UV optical modulators at 360 nm was fabricated. The modulators operated in a transverse geometry and consisted of a GaN active layer surrounded by transparent AlGaN insulating and electrical contact layers. The typical thickness of the GaN layer was 0.4 um so the effects of the electric field on the exciton resonance could be directly observed. A hydrogenic model for the bulk exciton was assumed. The applied electric field opposed the attractive coulomb potential between the electron and hole and broadens the exciton resonance. This results in more or less light through the device depending on the spectral position. To understand the magnitude of the applied field within the device structure a 1D Poisson Solver was used. Spontaneous polarization and piezoelectric effects due to lattice strain between the AlGaN and GaN layers were included in the model and were found to have influence on the device at lower operating voltages. In the electric field modulated devices a contrast ratio of about 20 percent was obtained. In thermally modulated devices, at low frequencies less than 200 Hz large shifts in the band edge led to large contrast ratios as expected. The temperature dependence of the device followed the Varshni relationship and allowed the magnitude of the temperature shift to be quantified. At higher frequencies from 1 kHz to 120 kHz an optical modulation of ˜5 percent was readily observed and was attributed to electronic effects. The limitation of 100 kHz was equipment related and it is conjectured that the modulation bandwidth would extend into the MHz.

Oberhofer, Andrew Edward

136

Structural, electronic, and dynamical properties of amorphous gallium arsenide: a comparison between two topological models  

E-print Network

Structural, electronic, and dynamical properties of amorphous gallium arsenide: a comparison of amorphous gallium arsenide. Using the recently­proposed ``activation­ relaxation technique'' and empirical

Lewis, Laurent J.

137

Corrosion development between liquid gallium and four typical metal substrates used in chip cooling device  

NASA Astrophysics Data System (ADS)

The limitation of the currently available thermal management method has put an ever serious challenge for computer chip designers. A liquid metal with low melting point around room temperature was recently identified as a powerful coolant of driving heat away because of its superior thermo-physical properties and the unique ability to be driven efficiently by a completely silent electromagnetic pump. However, the adoption of gallium, one of the best candidates as metal coolant so far, may cause serious corrosion to the structure materials and subsequently affect the performance or even dangerous running of the cooling system. To address this emerging critical issue, here the compatibility of gallium with four typical metal substrates (6063 Aluminum-Alloy, T2 Copper-Alloy, Anodic Coloring 6063 Aluminum-Alloy and 1Cr18Ni9 Stainless Steel) was comprehensively investigated in order to better understand the corrosion mechanisms and help find out the most suitable structure material for making a liquid metal cooling device. To grasp in detail the dynamic corrosion behavior, an image acquisition and contrasting method was developed. Moreover, corrosion morphology analyses were performed by means of scanning electron microscope (SEM). The chemical compositions of the corroded layers were evaluated using energy dispersive spectrometry (EDS). According to the experiments, it was found that, the corrosion of the 6063 Aluminum-Alloy was rather evident and serious under the temperature range for chip cooling. The loose corrosion product will not only have no protection for the inner substrate, but also accelerate the corrosion process. Compared to the 6063 Aluminum-Alloy, T2 Copper-Alloy showed a slow and general corrosion, but part of the corrosion product can shed from the substrate, which will accelerate corrosion action and may block the flowing channel. Anodic Coloring 6063 Aluminum-Alloy and 1Cr18Ni9 Stainless Steel were found to have excellent corrosion resistance among these four specimens. No evident corrosion phenomena were found under the examination of SEM and EDS when exposed for 30 days at the temperature of 60°C, which suggests their suitability as structure materials for the flow of liquid metal. However, as for the Anodic Coloring 6063 Aluminum-Alloy, surface treatment and protection are of vital importance. The present study is of significance for making a liquid metal chip cooling device which can actually be used in the future computer industry.

Deng, Yue-Guang; Liu, Jing

2009-06-01

138

Interactions of Zircaloy cladding with gallium: 1998 midyear status  

SciTech Connect

A program has been implemented to evaluate the effect of gallium in mixed-oxide (MOX) fuel derived from weapons-grade (WG) plutonium on Zircaloy cladding performance. The objective is to demonstrate that low levels of gallium will not compromise the performance of the MOX fuel system in a light-water reactor. The graded, four-phase experimental program was designed to evaluate the performance of prototypic Zircaloy cladding materials against (1) liquid gallium (Phase 1), (2) various concentrations of Ga{sub 2}O{sub 3} (Phase 2), (3) centrally heated surrogate fuel pellets with expected levels of gallium (Phase 3), and (4) centrally heated prototypic MOX fuel pellets (Phase 4). This status report describes the results of a series of tests for Phases 1 and 2. Three types of tests are being performed: (1) corrosion, (2) liquid metal embrittlement, and (3) corrosion-mechanical. These tests will determine corrosion mechanisms, thresholds for temperature and concentration of gallium that may delineate behavioral regimes, and changes in the mechanical properties of Zircaloy. Initial results have generally been favorable for the use of WG-MOX fuel. The MOX fuel cladding, Zircaloy, does react with gallium to form intermetallic compounds at {ge}300 C; however, this reaction is limited by the mass of gallium and is therefore not expected to be significant with a low level (parts per million) of gallium in the MOX fuel. Although continued migration of gallium into the initially formed intermetallic compound can result in large stresses that may lead to distortion, this was shown to be extremely unlikely because of the low mass of gallium or gallium oxide present and expected clad temperatures below 400 C. Furthermore, no evidence for grain boundary penetration by gallium has been observed.

Wilson, D.F.; DiStefano, J.R.; Strizak, J.P.; King, J.F.; Manneschmidt, E.T.

1998-06-01

139

Targeting Gallium to Cancer Cells through the Folate Receptor  

Microsoft Academic Search

The development of gallium(III) compounds as anti-cancer agents for both treatment and diagnosis is a rapidly developing ! eld of research. Problems remain in exploring the full potential of gallium(III) as a safe and successful therapeutic agent or as an imaging agent. One of the major issues is that gallium(III) compounds have little tropism for cancer cells. We have combined

Nerissa Viola-Villegas; Anthony Vortherms; Robert P. Doyle

140

Surface photovoltage spectroscopy applied to gallium arsenide surfaces  

NASA Technical Reports Server (NTRS)

The experimental and theoretical basis for surface photovoltage spectroscopy is outlined. Results of this technique applied to gallium arsenide surfaces, are reviewed and discussed. The results suggest that in gallium arsenide the surface voltage may be due to deep bulk impurity acceptor states that are pinned at the Fermi level at the surface. Establishment of the validity of this model will indicate the direction to proceed to increase the efficiency of gallium arsenide solar cells.

Bynik, C. E.

1975-01-01

141

(Data in kilograms of gallium content, unless noted) Domestic Production and Use: No domestic primary gallium recovery was reported in 1995. Two companies in  

E-print Network

.S. gallium consumption, were valued at about $3.5 million. Gallium arsenide (GaAs) components represented (MFN) Non-MFN2 12/31/95 12/31/95 Gallium metal 8112.91.1000 3.7% ad val. 25.0% ad val. Gallium arsenide wafers, undoped 2851.00.0010 2.8% ad val. 25.0% ad val. Gallium arsenide wafers, doped 3818.00.0010 Free

142

Ohmic contacting schemes to gallium arsenide devices  

NASA Astrophysics Data System (ADS)

The goal of this project was to design ohmic contacting schemes to gallium arsenide that would sustain 400C for 1 hour and 600C for 15 minutes without significant degradation. Our approach uses a generic contacting scheme calling for two thin-film layers between the semiconducting substrate and the metal overlayer: (1) a contacting layer adjacent to the semiconductor that determines the electrical properties of the contact, and (2) a diffusion barrier layer adjacent to the metal overlayer that assures the thermal stability of the contact. A contact designed according to this scheme (silver overlayer, pure tungsten or tungsten-nitrogen layer as the diffusion barrier, and a magnesium-doped platinum film for the contacting layer to p-type gallium arsenide) changes little upon annealing at 550C for 5 hours. The contact resistivity is on the order of 1E-3 ohm sq cm or less.

1987-08-01

143

Photonuclear Reaction Cross Sections for Gallium Isotopes  

E-print Network

The photon induced reactions which are named as photonuclear reactions have a great importance in many field of nuclear, radiation physics and related fields. Since we have planned to perform photonuclear reaction on gallium target with bremmstrahlung photons from clinical linear accelerator in the future, the cross-sections of neutron (photo-neutron ({\\gamma},xn)) and proton (photo-proton ({\\gamma},xn)) productions after photon activation have been calculated by using TALYS 1.2 computer code in this study. The target nucleus has been considered gallium which has two stable isotopes, 69Ga and 71Ga. According to the results, we have seen that the calculations are in harmony in the limited literature values. Furthermore, the pre-equilibrium and compound process contributions to the total cross-section have been investigated.

Serkan Akkoyun; Tuncay Bayram

2014-09-08

144

Graphene on gallium arsenide: Engineering the visibility  

Microsoft Academic Search

Graphene consists of single or few layers of crystalline ordered carbon atoms. Its visibility on oxidized silicon (Si\\/SiO2) enabled its discovery and spawned numerous studies of its unique electronic properties. The combination of graphene with the equally unique electronic material gallium arsenide (GaAs) has up to now lacked such easy visibility. Here we demonstrate that a deliberately tailored GaAs-aluminum arsenide

M. Friedemann; K. Pierz; R. Stosch; F. J. Ahlers

2009-01-01

145

The Baksan gallium solar neutrino experiment  

SciTech Connect

A radiochemical /sup 71/Ga-/sup 71/Ge experiment to determine the integral flux of neutrinos from the sun has been constructed at the Baksan Neutrino Observatory in the USSR. Measurements have begun with 30 tonnes of gallium. The experiment is being expanded with the addition of another 30 tonnes. The motivation, experimental procedures, and present status of this experiment are presented. 43 refs., 1 fig., 1 tab.

Gavrin, V.N.; Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.L.; Bychuk, O.V.; Danshin, S.N.; Eroshkina, L.A.; Faizov, E.L.; Gayevsky, V.I.; Girin, S.V.

1989-01-01

146

a Gallium Multiphase Equation of State  

NASA Astrophysics Data System (ADS)

A new SESAME multiphase Gallium equation of state (EOS) has been developed. It includes three of the solid phases (Ga I, Ga II, Ga III) and a fluid phase (liquid/gas). The EOS includes consistent latent heat between the phases. We compare the results to the liquid Hugoniot data. We also explore the possibility of re-freezing via dynamic means such as isentropic and shock compression. We predict an unusual spontaneous spreading of low pressure shocks from STP.

Crockett, Scott D.; Greeff, Carl W.

2009-12-01

147

Gallium-67 imaging in muscular sarcoidosis  

SciTech Connect

A case is presented of sarcoid myopathy in which radiogallium was seen to accumulate in the sites of muscle involvement. Uptake of the radiotracer disappeared following institution of corticosteroid therapy. The exceptional nature of this case contrasts with the high frequency of biopsy evidence of sarcoid granulomas in muscle. Gallium-67 imaging can be used to determine the extent of muscle involvement and, through evaluation of uptake intensity, the degree of disease activity before and after treatment.

Edan, G.; Bourguet, P.; Delaval, P.; Herry, J.Y.

1984-07-01

148

Gallium Nitride Schottky betavoltaic nuclear batteries  

Microsoft Academic Search

Gallium Nitride (GaN) Schottky betavoltaic nuclear batteries (GNBB) are demonstrated in our work for the first time. GaN films are grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD), and then GaN Schottky diodes are fabricated by normal micro-fabrication process. Nickel with mass number of 63 (63Ni), which emits ? particles, is loaded on the GaN Schottky diodes to

Min Lu; Guo-guang Zhang; Kai Fu; Guo-hao Yu; Dan Su; Ji-feng Hu

2011-01-01

149

Silicon solution for gallium arsenide IC's  

SciTech Connect

An analytical discussion is presented of the development of a new type of integrated circuit design. In this new technology, gallium arsenide is grown on silicon. The result is that the best characteristics of both semiconductors are combined. At the present time, the technology is still in the laboratory phase of development, but it appears likely that commercialization will be accomplished in the near future. 2 figures.

Robinson, A.L.

1986-05-16

150

Terbium Gallium garnet for Faraday Effect Devices  

Microsoft Academic Search

The magneto-optic crystal terbium gallium garnet (TGG) has been grown by the Czochralski process. Boules of 2-3 cm diameter and 10-15 cm long were obtained core, strain, and defect free. The properties of TGG are ideal for Faraday effect devices such as modulators and isolators. The Verdet constant has been measured from 500-1060 nm with values ranging from 0.75-0.12 min

D. J. Dentz; R. C. Puttbach; R. F. Belt

1974-01-01

151

Terbium Gallium garnet for Faraday Effect Devices  

Microsoft Academic Search

The magneto-optic crystal terbium gallium garnet (TGG) has been grown by the Czochralski process. Boules of 2–3 cm diameter and 10–15 cm long were obtained core, strain, and defect free. The properties of TGG are ideal for Faraday effect devices such as modulators and isolators. The Verdet constant has been measured from 500–1060 nm with values ranging from 0.75–0.12 min

D. J. Dentz; R. C. Puttbach; R. F. Belt

1974-01-01

152

The photorefractive effect in terbium gallium garnet  

Microsoft Academic Search

A photorefractive effect in terbium gallium garnet with refractive index changes up to ?n = 5 × 10?8 for elementary volume phase holograms is reported. The light-induced refractive index changes can directly be attributed via Kramers-Kronig relations to the observed photochromic and light-induced, linear dichroitic behavior. This can also explain the possibility of writing holograms with orthogonally polarized beams.

L. Ackermann

1995-01-01

153

Photochromism of doped terbium gallium garnet  

NASA Astrophysics Data System (ADS)

In order to understand the photochromic effect in terbium gallium garnet doubly doped with calcium and cerium, the spectral characteristics of absorption changes induced by heating and irradiation are studied. Based on the findings we conclude that the photochromic band at 420nm originates from defects involving Tb4+ . Previously the band was attributed to Ce3+ . Two possible models are suggested and discussed, both of which are in agreement with the obtained experimental results.

Dachraoui, H.; Rupp, R. A.; Lengyel, K.; Ellabban, M. A.; Fally, M.; Corradi, G.; Kovács, L.; Ackermann, L.

2006-10-01

154

Photorefractive effect in terbium gallium garnet  

Microsoft Academic Search

Terbium gallium garnet is an interesting representative of the family of rare-earth garnets. In these crystal we have observed a photorefractive effect. This effect is probably linked to the light-induced dichroitic and photochromic behavior of this crystal. Using Kramers-Kronig-relations an estimation shows that the light-induced absorption changes can explain the observed refractive index changes. The observation of holographic writing with

I. Amin; B. Sugg; Martin Fally; Romano A. Rupp

2002-01-01

155

Gallium-assisted transfer hydrogenation of alkenes.  

PubMed

We report a rare case of alkene transfer hydrogenation using a main-group compound instead of a transition-metal complex as catalyst. We disclosed that 1,4-cyclohexadiene can be used as H2 surrogate towards olefin reduction in the presence of [IPrGaCl2 ][SbF6 ]. Hydrogenative cyclizations have also been carried out because this cationic gallium complex is also a potent hydroarylation catalyst. PMID:25213294

Michelet, Bastien; Bour, Christophe; Gandon, Vincent

2014-10-27

156

Gallium arsenide for devices and integrated circuits  

SciTech Connect

Gallium Arsenide has long been hailed as the material of the future and it is only in recent years that the technology associated with its growth and processing has matured to the point where IC production can be contemplated at the industrial level. This point has now been reached and the electronics industries in Europe, the USA and Japan are actively moving from research activities into product development using this and related material. The text is divided into 15 chapters: Gallium Arsenide: Physical and Transport Properties; Liquid phase and Vapour Phase Epitaxy of GaAs and Related Compounds; Expitaxial Growth and GaAs: MBE and MOCVD; Characterization of GaAs I: Electrical Techniques; Characterization of GaAsII: Ion Beam Analysis; Ion Implantation; Wet and Dry Processing GaAs; Microwave and Millimetre - Wave Diodes; GaAs Mesfet's and High Electron Mobility Transistors (HEMT); Optoelectronic Devices and Components; Gallium Arsenide Monolithic Microwave Integrated Circuits; GaAs Digital Integrated Circuits; III-V Semiconductors for Solar Cells.

Morgan, D.V.; Thomas, H.

1986-01-01

157

One-dimensional zigzag gallium nitride nanostructures  

NASA Astrophysics Data System (ADS)

Two one-dimensional (1D) single-crystalline gallium nitride (GaN) nanostructures with periodic zigzag (type I) and diameter-modulated (type II) shapes have been synthesized by passing through ammonia over a mixture of gallium and gallium oxide (Ga2O3) powders held at elevated temperature. The process was catalyzed by the dispersion of thio-capped Au nanoparticles on the substrate onto which GaN nanostructures were condensed. The transformation between these two nanostructure morphologies was also observed. A possible growth model for the zigzag-shaped nanostructures is proposed, in which the formation of the zigzag nanostructures results from the construction of two different nanoscale unit cells. This work provides an avenue to a group of 1D nanostructures with a zigzag shape. The possibility to form 1D nanostructures yet to be discovered by changing the stacking direction of the (0001) plane will facilitate the fabrication of nanoscale functional devices as well as our understanding of the growth behavior of nanoscale crystallites.

Zhou, X. T.; Sham, T. K.; Shan, Y. Y.; Duan, X. F.; Lee, S. T.; Rosenberg, R. A.

2005-05-01

158

Electronic Transport Characteristics of Gallium Nitride Nanowire-based Nanocircuits  

E-print Network

of gallium nitride based three terminal field effect transistors fabricated via electron beam lithography and drain contacts were patterned using electron beam lithography, with Ti/Au used for the conducting sourceElectronic Transport Characteristics of Gallium Nitride Nanowire-based Nanocircuits V.M. Ayres, B

Ayres, Virginia

159

Effect of Gallium Nitrate on Experimental Autoimmune Uveitis  

Microsoft Academic Search

Gallium nitrate (GN) has been shown to inhibit T cell-mediated inflammatory disease. The purpose of our study was to test the effect of gallium nitrate (GN) on experimental autoimmune uveitis (EAU). Experimental autoimmune uveitis was induced in male Lewis rats immunized with retinal S-antigen. Rats received subcutaneous injections of GN or saline one day prior to immunization and 1, 4,

MARK C. LOBANOFF; ALEXANDER T. KOZHICH; DANIEL I. MULLET; NICHOLAS GERBER; IGAL GERY; CHI-CHAO CHAN; SCOTT M. WHITCUP

1997-01-01

160

Two octanuclear gallium metallamacrocycles of topologically different connectivities.  

PubMed

Two topologically different metallamacrocycles--S8 symmetric octanuclear gallium(III) metalladiazamacrocycle and pseudo-D4 symmetric octanuclear gallium(III) metalladiazamacrocycle--could be prepared using two similar heteroditopic bridging ligands having asymmetrical tridentate-bidentate binding residues. PMID:18026590

Park, Mira; John, Rohith P; Moon, Dohyun; Lee, Kyungjin; Kim, Ghyung Hwa; Lah, Myoung Soo

2007-12-14

161

GALLIUM--2003 28.1 References that include a section mark () are found in the Internet  

E-print Network

to propel the increase in gallium consumption. Gallium arsenide (GaAs) wafers, however, continuedGALLIUM--2003 28.1 1 References that include a section mark (§) are found in the Internet References Cited section. GALLIUM By Deborah A. Kramer Domestic survey data and tables were prepared

162

Microstructures of gallium nitride nanowires synthesized by oxide-assisted method  

E-print Network

), germanium (Ge), gallium arsenide (GaAs) and gallium phosphide (GaP). In the fabricating pro- cess, oxidesMicrostructures of gallium nitride nanowires synthesized by oxide-assisted method W.S. Shi, Y Received 10 March 2001; in ®nal form 3 August 2001 Abstract Gallium nitride (GaN) nanowires were

Zheng, Yufeng

163

Laser photochemistry of gallium-containing compounds. [Trimethylgallium  

SciTech Connect

The production of gas-phase gallium atoms in the photolysis of trimethylgallium has been investigated at 193 nm and at other laser wavelengths. Ground state (4 /sup 2/P/sup 0//sub 1/2) and metastable (4 /sup 2/P/sup 0//sub 3/2/) gallium atoms are detected using laser-induced fluorescence techniques. Our results indicate that gallium atoms continue to be produced at long times after the laser pulse. The observed dependence on photolysis laser fluence, trimethylgallium pressure, and buffer gas pressure are consistent with a mechanism in which highly excited gallium methyl radicals undergo unimolecular decomposition to produce gallium atoms. Since this process is observed to happen on the time scale of hundreds of microseconds, these results have important implications for studies of metal deposition and direct laser writing by laser photolysis of organometallic compounds. 31 refs., 5 figs.

Baughcum, S.L.; Oldenborg, R.C.

1986-01-01

164

The Preparation and Structural Characterization of Three Structural Types of Gallium Compounds Derived from Gallium (II) Chloride  

NASA Technical Reports Server (NTRS)

The three compounds Ga2Cl4(4-mepy)2 (1),[GaCl2(4-mepy)4]GaCl4x1/2(4-mepy); (2) and GaCl2(4-mepy)2(S2CNEt2); (3) (4-mepy= 4-methylpyridine) have been prepared from reactions of gallium (II) chloride in 4-methylpyridine and characterized by single-crystal X-ray analysis. Small variations in the reaction conditions for gallium(II) chloride can produce crystals with substantially different structural properties. The three compounds described here encompass a neutral gallium(II) dimer in which each gallium is four-coordinate, an ionic compound containing both anionic and cationic gallium complex ions with different coordination numbers and a neutral six-coordinate heteroleptic

Gordon, Edward M.; Hepp, Aloysius F.; Duraj. Stan A.; Habash, Tuhfeh S.; Fanwick, Phillip E.; Schupp, John D.; Eckles, William E.; Long, Shawn

1997-01-01

165

Gallium-67 imaging in muscular sarcoidosis  

SciTech Connect

A case is presented of sarcoid myopathy in which radiogallium was seen to accumulate in the sites of muscle involvement. Uptake of the radiotracer disappeared following institution of corticosteroid therapy. The exceptional nature of this case contrasts with the high frequency of biopsy evidence of sarcoid muscle disease but is consistent with the rarity of clinical evidence of sarcoid granulomas in muscle. Gallium-67 imaging can be used to determine the extent of muscle involvement and, through evaluation of uptake intensity, the degree of disease activity before and after treatment.

Edan, G.; Bourguet, P.; Delaval, P.; Herry, J.Y.

1984-07-01

166

Strong field processes inside gallium arsenide  

NASA Astrophysics Data System (ADS)

We demonstrated experimentally that the multiphoton ionization rate in gallium arsenide depends on the alignment of the laser polarization with respect to the crystal axis. We observed modulation in the ionization rate of a linearly-polarized 1900 nm laser beam directly by measuring its transmission while rotating the crystal, without Fourier analysis. We propose that the modulation in the ionization rate arises from periodic variation in the reduced carrier mass, as predicted by Keldysh theory. We show direct comparison of the experimental transmission modulation depth with Keldysh?s non-resonant ionization theory for solids. This opens up a novel method for non-invasive crystallography of semiconductor materials.

Golin, S. M.; Kirkwood, S. E.; Klug, D. D.; Villeneuve, D. M.; Rayner, D. M.; Trallero Herrero, C. A.; Corkum, P. B.

2014-10-01

167

Photorefractive effect in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

Terbium gallium garnet is an interesting representative of the family of rare-earth garnets. In these crystal we have observed a photorefractive effect. This effect is probably linked to the light-induced dichroitic and photochromic behavior of this crystal. Using Kramers-Kronig-relations an estimation shows that the light-induced absorption changes can explain the observed refractive index changes. The observation of holographic writing with orthogonally polarized beams may by attribute to orientationally non- equivalent centers, which become anisotropic by the absorption of light after illumination. Yet, the nature of these centers is unclear. Further studies are already under way to clarify this point.

Amin, I.; Sugg, B.; Fally, Martin; Rupp, Romano A.

2002-02-01

168

Assessment of gallium-67 scanning in pulmonary and extrapulmonary sarcoidosis  

SciTech Connect

Gallium-67 scans have been widely employed in patients with sarcoidosis as a means of indicating alveolitis and the need for corticosteroid therapy. Observation of 32 patients followed 3 or more years after gallium scans showed no correlation between findings and later course: of 10 patients with pulmonary uptake, 7 recovered with minor residuals; of 18 patients with mediastinal of extrathoracic uptake, 10 had persistent or progressive disease; of 4 patients with negative initial scans, 2 had later progression. The value of gallium-67 scans as an aid to diagnosis was studied in 40 patients with extrapulmonary sarcoidosis. In 12 patients, abnormal lacrimal, nodal, or pulmonary uptake aided in selection of biopsy sites. Gallium-67 scans and serum ACE levels were compared in 97 patients as indices of clinical activity. Abnormal gallium-67 uptake was observed in 96.3% of the tests in active disease, and ACE level elevation occurred in 56.3%. In 24 patients with inactive or recovered disease, abnormal gallium-67 uptake occurred in 62.5% and ACE level elevation in 37.5%. Gallium-67 scans have a limited but valuable role in the diagnosis and management of sarcoidosis.

Israel, H.L.; Gushue, G.F.; Park, C.H.

1986-01-01

169

Doped gallium oxide nanowires for photonics  

NASA Astrophysics Data System (ADS)

Monoclinic gallium oxide, ?-Ga2O3, is a transparent conducting oxide (TCO) that presents one of the widest band gaps among this family of materials. Its characteristics make it highly interesting for applications in UV - visible - IR optoelectronic and photonic devices. On the other hand, the morphology of nanowires made of this oxide presents specific advantages for light emitting nanodevices, waveguides and gas sensors. Control of doping of the nanostructures is of the utmost importance in order to tailor the behavior of these devices. In this work, the growth of the nanowires is based on the vapor-solid (VS) mechanism during thermal annealing treatment while the doping process was carried out in three different ways. In one of the cases, doping was obtained during the growth of the wires. A second method was based on thermal diffusion of the dopants after the growth of undoped nanowires, while the third method used ion implantation to introduce optically active ions into previously grown nanowires. The study of the influence of the different dopants on the luminescence properties of gallium oxide nanowires is presented. In particular, transition metals and rare earths such as Cr, Gd, Er or Eu were used as optically active dopants that allowed selection of the luminescence wavelength, spanning from the UV to the IR ranges. The benefits and drawbacks of the three different doping methods are analyzed. The waveguiding behavior of the doped nanowires has been studied by room temperature micro-photoluminescence.

Nogales, E.; López, I.; Méndez, B.; Piqueras, J.; Lorenz, K.; Alves, E.; García, J. A.

2012-02-01

170

Characterization of semi-insulating gallium arsenide  

NASA Astrophysics Data System (ADS)

This project was established for the purpose of characterization of samples from melt grown single crystals of nominally undoped gallium arsenide, primarily such crystals as grown by the vertical zone melt (VZM) method at the Naval Research Laboratory. During this period electrical and optical samples were measured for 13 of these VZM-grown gallium arsenide. Measurements made at Western Washington University (WWU) under the terms of this project were in accordance with the Statement of Work provided at the project's outset: including near-infrared transmittance measurements for determination of neutral and ionized EL2 center concentrations, local vibrational mode (LVM) measurements in the mid-IR relative to carbon impurities, and measurements of dc electrical transport properties versus temperature. A program for growth of GaAs and other semiconductors by the VZM method began at NRL several years ago, and the practicality of this method for growing semi-insulating (SI) nominally undoped GaAs in a pBN crucible was demonstrated by Swiggard (1989) and in various subsequent papers.

Blakemore, John S.

1991-08-01

171

Gallium scanning in lymphoid interstitial pneumonitis of children with AIDS  

SciTech Connect

Lymphoid interstitial pneumonitis (LIP) is a frequent pulmonary complication in the child with the acquired immune deficiency syndrome (AIDS) and human immunodeficiency virus (HIV) infection. We report the gallium scan findings in two children with AIDS and LIP. Gallium scintigraphy in both children demonstrated increased radionuclide concentration throughout the lungs, a pattern indistinguishable scintigraphically from that of Pneumocystis carinii pneumonia (PCP). This should alert nuclear medicine practitioners and referring physicians to another cause of diffusely increased gallium uptake in the lungs of patients with AIDS.

Schiff, R.G.; Kabat, L.; Kamani, N.

1987-12-01

172

Microencapsulation of gallium-indium (Ga-In) liquid metal for self-healing applications.  

PubMed

Microcapsules containing a liquid metal alloy core of gallium-indium (Ga-In) are prepared via in situ urea-formaldehyde (UF) microencapsulation. The capsule size, shape, thermal properties, and shell wall thickness are investigated. We prepare ellipsoidal capsules with major and minor diameter aspect ratios ranging from 1.64 to 1.08 and with major diameters ranging from 245?µm to 3?µm. We observe that as the capsule major diameter decreases, the aspect ratio approaches 1. The thermal properties of the prepared microcapsules are investigated by thermogravimetric (TGA) and differential scanning calorimetry (DSC). Microcapsules are shown to survive incorporation into an epoxy matrix and to trigger via mechanical damage to the cured matrix. Microcapsules containing liquid metal cores may have diverse applications ranging from self-healing to contrast enhancement or the demonstration of mechano-adaptive circuitry. PMID:24495196

Blaiszik, B J; Jones, A R; Sottos, N R; White, S R

2014-01-01

173

Measurement of arsenic and gallium content of gallium arsenide semiconductor waste streams by ICP-MS.  

PubMed

The chemistry of semiconductor wafer processing liquid waste, contaminated by heavy metals, was investigated to determine arsenic content. Arsenic and gallium concentrations were determined for waste slurries collected from gallium arsenide (GaAs) wafer processing at three industrial sources and compared to slurries prepared under laboratory conditions. The arsenic and gallium content of waste slurries was analyzed using inductively coupled plasma mass-spectrometry (ICP-MS) and it is reported that the arsenic content of the waste streams was related to the wafer thinning process, with slurries from wafer polishing having the highest dissolved arsenic content at over 1,900 mgL(-1). Lapping slurries had much lower dissolved arsenic (< 90 mgL(-1)) content, but higher particulate contents. It is demonstrated that significant percentage of GaAs becomes soluble during wafer lapping. Grinding slurries had the lowest dissolved arsenic content at 15 mgL(-1). All three waste streams are classified as hazardous waste, based on their solids content and dissolved arsenic levels and treatment is required before discharge or disposal. It is calculated that as much as 93% of material is discarded through the entire GaAs device manufacturing process, with limited recycling. Although gallium can be economically recovered from waste slurries, there is little incentive to recover arsenic, which is mostly landfilled. Options for treating GaAs processing waste streams are reviewed and some recommendations made for handling the waste. Therefore, although the quantities of hazardous waste generated are miniscule in comparison to other industries, sustainable manufacturing practices are needed to minimize the environmental impact of GaAs semiconductor device fabrication. PMID:20390892

Torrance, Keith W; Keenan, Helen E; Hursthouse, Andrew S; Stirling, David

2010-01-01

174

The dimeric nature of bonding in gallium: from small clusters to the ?-gallium phase.  

PubMed

We consider the structural similarity of small gallium clusters to the bulk structure of ?-gallium, which has been previously described as a molecular metal, via density functional theory-based computations. Previous calculations have shown that the tetramer, the hexamer, and the octamer of gallium are all structurally similar to the ?-phase. We perform an analysis of the bonding in these clusters in terms of the molecular orbitals and atoms in molecules description in order to assess whether we can see similarities at these sizes to the bonding pattern, which is ascribed to the co-existence of covalent and metallic bonding in the bulk. The singlet Ga4 and Ga8 clusters can be constructed in a singlet ground state from the Ga-dimers in the first excited triplet state of the Ga2-molecule, the (3)?g(-) state. Molecular orbital (MO) analysis confirms that the dimer is an essential building block of these small clusters. Comparison of the AIM characteristics of the bonds within the clusters to the bonds in the bulk ?-phase supports the identification of the covalent bond in the bulk as related to the (3)?g(-) state of the dimer. PMID:25294298

Tonner, Ralf; Gaston, Nicola

2014-10-21

175

Computer simulation of radiation damage in gallium arsenide  

NASA Technical Reports Server (NTRS)

A version of the binary-collision simulation code MARLOWE was used to study the spatial characteristics of radiation damage in proton and electron irradiated gallium arsenide. Comparisons made with the experimental results proved to be encouraging.

Stith, John J.; Davenport, James C.; Copeland, Randolph L.

1989-01-01

176

Ellipsometric study of silicon nitride on gallium arsenide  

NASA Technical Reports Server (NTRS)

A method for optimizing the sensitivity of ellipsometric measurements for thin dielectric films on semiconductors is described in simple physical terms. The technique is demonstrated for the case of sputtered silicon nitride films on gallium arsenide.

Alterovitz, S. A.; Bu-Abbud, G. H.; Woollam, J. A.; Liu, D.; Chung, Y.; Langer, D.

1982-01-01

177

Generator for ionic gallium-68 based on column chromatography  

DOEpatents

A physiologically acceptable solution of gallium-68 fluorides, having an activity of 0.1 to 50 millicuries per milliliter of solution is provided. The solution is obtained from a generator comprising germanium-68 hexafluoride bound to a column of an anion exchange resin which forms gallium-68 in situ by eluting the column with an acid solution to form a solution containing .sup.68 Ga-fluorides. The solution then is neutralized prior to administration.

Neirinckx, Rudi D. (Medfield, MA); Davis, Michael A. (Westwood, MA)

1981-01-01

178

X ray topography study of gallium phosphate crystals and resonators  

Microsoft Academic Search

Using the synchrotron radiation delivered by the DCI storage ring at LURE (Orsay, France), the X-ray topography technique was used to study the crystalline perfection of GaPO4 samples grown under different conditions. The growth of gallium phosphate on a berlinite seed is analyzed by X-ray section topography. The results obtained demonstrate the feasibility of gallium phosphate epitaxy on large berlinite

B. Capelle; A. Zarka; J. Schwartzel; J. Detaint; Y. Zheng; A. Ibanez; E. Philippot

1993-01-01

179

Complexometric determination of gallium with calcein blue as indicator  

USGS Publications Warehouse

A metalfluorechromic indicator, Calcein Blue, has been used for the back-titration of milligram amounts of EDTA in presence of gallium complexes. The indicator was used in conjunction with an ultraviolet titration assembly equipped with a cadmium sulphide detector cell and a microammeter for enhanced end-point detection. The result is a convenient and rapid method with an accuracy approaching 0.1 % and a relative standard deviation of about 0.4% for 10 mg of gallium. ?? 1967.

Elsheimer, H. N.

1967-01-01

180

Complexometric determination of gallium with calcein blue as indicator.  

PubMed

A metalfluorechromic indicator, Calcein Blue, has been used for the back-titration of milligram amounts of EDTA in presence of gallium complexes. The indicator was used in conjunction with an ultraviolet titration assembly equipped with a cadmium sulphide detector cell and a microammeter for enhanced end-point detection. The result is a convenient and rapid method with an accuracy approaching 0.1% and a relative standard deviation of about 0.4% for 10 mg of gallium. PMID:18960071

Elsheimer, H N

1967-01-01

181

Gallium67 citrate in human tumors: ultrastructural localization by autoradiography  

Microsoft Academic Search

The purpose of this study is to demonstrate the localization of carrier-free ⁶⁷gallium citrate in a variety of human tumors using electron microscopic autoradiography. Multiorgan surgical specimens were obtained from 76 patients with a variety of tumors 24 to 96 hours following intravenous administration of 45 microcuries per kilogram of body weight of carrier-free gallium-67. Specimens received for electron microscopy

O. L. Manfredi; L. R. Weiss

1978-01-01

182

Electrical contacts to ion cleaned n-type gallium arsenide.  

NASA Technical Reports Server (NTRS)

The electrical current through silver contacts evaporated onto n-type gallium arsenide is reported as a function of surface treatment. Contacts to untreated gallium arsenide exhibit the expected high resistance. Surface cleaning by argon ion bombardment reduces the resistance by three orders of magnitude. The electrical resistance beyond 850 eV increases rapidly with ion bombardment energy. The resistance minimum at 850 eV is explained semiquantitatively in terms of a balance between cleaning and surface damage.

Walker, G. H.; Conway, E. J.

1972-01-01

183

In-situ X-ray photoelectron spectroscopy study of supported gallium oxide  

NASA Astrophysics Data System (ADS)

In-situ XPS study of supported gallium oxide catalysts prepared by impregnation of different metal oxides supports (SiO 2, ?-Al 2O 3, TiO 2, and MgO) has been performed. It has been found that the formation of metallic gallium takes place upon high-temperature reduction of the catalysts in flowing hydrogen. Relative concentrations of metallic gallium were most high in the cases of alumina- and titania-supported catalysts. It was suggested that interaction of gallium oxide with a support surface favors the formation of metallic gallium upon high-temperature reduction. A possible mechanism of metallic gallium formation upon the reduction is discussed.

Serykh, Alexander I.; Amiridis, Michael D.

2010-06-01

184

The Soviet-American Gallium Experiment (SAGE)  

SciTech Connect

It is a great pleasure for me to have been asked by Louis Rosen to tell you about the Soviet-American Gallium Experiment (SAGE). This undertaking is a multi-institutional collaboration among scientists from the Institute for Nuclear Research, Moscow (INR), Los Alamos National Laboratory (LANL), and several US universities. Its purpose is to measure the number of low-energy electron neutrinos emitted from the Sun that arrive at this planet. As such, it is an extremely important experiment, touching on fundamental physics issues as well as solar dynamics. In contrast to the strategic overviews, plans, and hopes for international collaboration presented earlier today, SAGE is an ongoing working effort with high hopes of producing the first measurement of the Sun's low-energy neutrino flux. This paper reviews this experiment. 3 refs., 3 figs.

Garvey, G.T.

1989-01-01

185

Radiation damage of gallium arsenide production cells  

NASA Technical Reports Server (NTRS)

High-efficiency gallium arsenide cells, made by the liquid epitaxy method (LPE), have been irradiated with 1-MeV electrons up to fluences of 10 to the 16th e/sq cm. Measurements have been made of cell spectral response and dark and light-excited current-voltage characteristics and analyzed using computer-based models to determine underlying parameters such as damage coefficients. It is possible to use spectral response to sort out damage effects in the different cell component layers. Damage coefficients are similar to other reported in the literature for the emitter and buffer (base). However, there is also a damage effect in the window layer and possibly at the window emitter interface similar to that found for proton-irradiated liquid-phase epitaxy-grown cells. Depletion layer recombination is found to be less than theoretically expected at high fluence.

Mardesich, N.; Garlick, G. F. J.

1987-01-01

186

Gallium arsenide solar array subsystem study  

NASA Technical Reports Server (NTRS)

The effects on life cycle costs of a number of technology areas are examined for a gallium arsenide space solar array. Four specific configurations were addressed: (1) a 250 KWe LEO mission - planer array; (2) a 250 KWe LEO mission - with concentration; (3) a 50 KWe GEO mission planer array; (4) a 50 KWe GEO mission - with concentration. For each configuration, a baseline system conceptual design was developed and the life cycle costs estimated in detail. The baseline system requirements and design technologies were then varied and their relationships to life cycle costs quantified. For example, the thermal characteristics of the baseline design are determined by the array materials and masses. The thermal characteristics in turn determine configuration, performance, and hence life cycle costs.

Miller, F. Q.

1982-01-01

187

Liquid membrane processes for gallium recovery from alkaline solutions  

SciTech Connect

Gallium is an important material in the semiconductor industry. Intermetallic compounds with gallium have applications as high-temperature rectifiers and transistors, solar batteries, and other devices where the photovoltaic effect can be used. In this paper, the authors examine the possibility of using membrane extraction and supported liquid membranes to recover gallium from alkaline solutions. Membrane extraction proves to be an alternative process to recover gallium from such liquors. In order to maximize mass transfer, highly hydrophilic membranes should be used in both the membrane extraction and stripping processes. The optimum composition of the membrane extractant is 10--15% Kelex 100, 10% n-decanol, 5% Versatic 10, and kerosene (vol %). The highest gallium permeability was obtained when the feed solution contained about 1.5 mol/l sodium hydroxide. The supported liquid membrane used failed to transport gallium because of instability. The dominant mechanisms for failure are considered to be spontaneous formation of a water-in-oil emulsion and formation of precipitates, causing membrane pore obstruction.

Zha, F.F.; Fane, A.G.; Fell, C.J.D. [Univ. of New South Wales, Sydney, New South Wales (Australia). UNESCO Centre for Membrane Science and Technology

1995-05-01

188

Inhalation developmental toxicology studies: Gallium arsenide in mice and rats  

SciTech Connect

Gallium arsenide is a crystalline compound used extensively in the semiconductor industry. Workers preparing solar cells and gallium arsenide ingots and wafers are potentially at risk from the inhalation of gallium arsenide dust. The potential for gallium arsenide to cause developmental toxicity was assessed in Sprague- Dawley rats and CD-1 (Swiss) mice exposed to 0, 10, 37, or 75 mg/m{sup 3} gallium arsenide, 6 h/day, 7 days/week. Each of the four treatment groups consisted of 10 virgin females (for comparison), and {approx}30 positively mated rats or {approx}24 positively mated mice. Mice were exposed on 4--17 days of gestation (dg), and rats on 4--19 dg. The day of plug or sperm detection was designated as 0 dg. Body weights were obtained throughout the study period, and uterine and fetal body weights were obtained at sacrifice (rats, 20 dg; mice, 18 dg). Implants were enumerated and their status recorded. Live fetuses were sexed and examined for gross, visceral, skeletal, and soft-tissue craniofacial defects. Gallium and arsenic concentrations were determined in the maternal blood and uterine contents of the rats (3/group) at 7, 14, and 20 dg. 37 refs., 11 figs., 30 tabs.

Mast, T.J.; Greenspan, B.J.; Dill, J.A.; Stoney, K.H.; Evanoff, J.J.; Rommereim, R.L.

1990-12-01

189

Ordre magnétique électronique induit par les interactions hyperfines dans les grenats de gallium-holmium et de gallium-terbium  

Microsoft Academic Search

2014 L'ordre magnétique observé dans les grenats de terbium-gallium et d'holmium- gallium à 0,25 et 0,19 K par mesure de susceptibilité et de chaleur spécifique est interprété dans un modèle à 2 singulets électroniques dans lequel on tient compte du couplage hyperfin et où les interactions magnétiques, essentiellement d'origine dipolaire, sont traitées dans l'approximation du champ moléculaire. Ce modèle se

J. HAMMANN; P. Manneville

1973-01-01

190

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2011 CFR

...Applicability: Description of the primary and secondary germanium and gallium...NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium...Applicability: Description of the primary and secondary germanium and...

2011-07-01

191

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2013 CFR

...Applicability: Description of the primary and secondary germanium and gallium...NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium...Applicability: Description of the primary and secondary germanium and...

2013-07-01

192

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2012 CFR

...Applicability: Description of the primary and secondary germanium and gallium...NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium...Applicability: Description of the primary and secondary germanium and...

2012-07-01

193

40 CFR 421.180 - Applicability: Description of the primary and secondary germanium and gallium subcategory.  

Code of Federal Regulations, 2010 CFR

...Applicability: Description of the primary and secondary germanium and gallium...NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY Primary and Secondary Germanium and Gallium...Applicability: Description of the primary and secondary germanium and...

2010-07-01

194

Samarium- and ytterbium-promoted oxidation of silicon and gallium arsenide surfaces  

SciTech Connect

A method is described for promoting oxidation of a silicon or gallium arsenide surface comprising: depositing a ytterbium overlayer on the silicon or gallium arsenide surface prior to the oxidation of the surface.

Franciosi, A.

1989-02-21

195

New chelation clean process for removing gallium from the focused-ion-beam repaired mask  

Microsoft Academic Search

Repairing mask defects with Focused Ion Beam (FIB) of gallium often results in a gallium-implanted area due to scan. This implanted layer reduces the light transmission by up to 10 ~ 30 percent, depending on the wavelength. This effect of localized transmission loss becomes printable at the extremes of focus-energy matrix of wafer printing. The existing methods for the gallium

Same-Ting Chen; Tzy-Ying Lin; Chue-San Yoo

2003-01-01

196

IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption  

E-print Network

IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption flat gallium arsenide solar cell, we show that it is possible to modify the flow of light and enhance material which directly contributes to the pho- tocurrent enhancement of the solar cell. Index Terms--Gallium

Grandidier, Jonathan

197

Pure silver ohmic contacts to N- and P- type gallium arsenide materials  

SciTech Connect

Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components an n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffused layer and the substrate layer, wherein the n-type layer comprises a substantially low doping carrier concentration.

Hogan, Stephen J. (Golden, CO)

1986-01-01

198

HOT CARRIER SPACE AND TIME DEPENDENT TRANSIENTS IN SHORT CHANNEL GALLIUM ARSENIDE DEVICES55  

E-print Network

HOT CARRIER SPACE AND TIME DEPENDENT TRANSIENTS IN SHORT CHANNEL GALLIUM ARSENIDE DEVICES55 Hr in gallium arsenide when the fields change temporally and spatially at a finite rate. For temporal changes gallium arsenide when f i e l d s change a t f i n i t e r a t e s and t o suggest the types

Paris-Sud XI, Université de

199

May 20, 2010 Growing gallium arsenide in thick multilayer stacks could make a big  

E-print Network

optics.org NEWS May 20, 2010 Growing gallium arsenide in thick multilayer stacks could make a big the technique for gallium arsenide (GaAs), the team hopes that its method will be equally applicable to other material systems such as gallium nitride and indium phosphide (Nature 465 329). "We can generate compound

Rogers, John A.

200

THE PREPARATION AND STUDY OF THE OPTICAL ABSORPTION EDGE OF THIN FILMS OF GALLIUM ARSENIDE  

E-print Network

212. THE PREPARATION AND STUDY OF THE OPTICAL ABSORPTION EDGE OF THIN FILMS OF GALLIUM ARSENIDE Par of gallium arsenide have been prepared by evaporation on to amorphous substrates. A simple and effective method of evaporating gallium arsenide, which would also be applicable to other III-V compounds

Boyer, Edmond

201

Electrochemical passivation of gallium arsenide surface with organic self-assembled monolayers in aqueous electrolytes  

E-print Network

Electrochemical passivation of gallium arsenide surface with organic self-assembled monolayers-assembled monolayers of octadecylthiol ODT were reconstituted on freshly etched gallium arsenide (n on electro-optical devices.1,2 Among various semiconductors, gallium arsenide GaAs is a promising material

Deutschmann, Rainer

202

DNA Detection Using Plasmonic Enhanced Near-Infrared Photoluminescence of Gallium Arsenide  

E-print Network

DNA Detection Using Plasmonic Enhanced Near-Infrared Photoluminescence of Gallium Arsenide Longhua is important for diagnostics and biomedical research. Herein, we report the use of gallium arsenide (Ga be utilized to develop innovative sensing systems.7 Gallium arsenide (GaAs), in particular, is an attractive

Li, Xiuling

203

Oxide-assisted growth and optical characterization of gallium-arsenide nanowires  

E-print Network

Oxide-assisted growth and optical characterization of gallium-arsenide nanowires W. S. Shi, Y. FAs nanowires. © 2001 American Institute of Physics. DOI: 10.1063/1.1371966 Gallium arsenide GaAs , as a direct mol % gallium oxide Ga2O3 at room temperature. The target and a polished silicon 100 substrate were

Zheng, Yufeng

204

Femtosecond laser ablation of gallium arsenide investigated with time-of-flight mass spectroscopy  

E-print Network

Femtosecond laser ablation of gallium arsenide investigated with time- of-flight mass spectroscopy laser-induced ablation of gallium arsenide using time-of-flight mass spectroscopy. At the ablation into a collisional expansion process. Above the ablation threshold, the behavior of gallium particles can

von der Linde, D.

205

Analysis of the growth modes for gallium arsenide metalorganic vapor-phase epitaxy  

E-print Network

Analysis of the growth modes for gallium arsenide metalorganic vapor-phase epitaxy D. C. Law March 2000 The surface roughness of gallium arsenide 001 films produced by metalorganic vapor for gallium surface diffusion has been estimated: Ed 1.35 0.1 eV. © 2000 American Institute of Physics. S0021

Li, Lian

206

Journal of Crystal Growth 286 (2006) 197204 Low-temperature atomic assembly of stoichiometric gallium arsenide  

E-print Network

gallium arsenide from equiatomic vapor D.A. Murdick�, X.W. Zhou, H.N.G. Wadley Department of Materials­Weber potential; A3. Molecular beam epitaxy; A3. Vapor deposition epitaxy; B1. Gallium arsenide 1. Introduction Ga amorphous structure. The atomic assembly mechanisms of arsenic dimer incorporation, as well as gallium

Wadley, Haydn

207

Process for forming pure silver ohmic contacts to N- and P-type gallium arsenide materials  

DOEpatents

Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components a n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffuse layer and the substrate layer wherein the n-type layer comprises a substantially low doping carrier concentration.

Hogan, S.J.

1983-03-13

208

Gallium scintigraphy in a case of septic cavernous sinus thrombosis  

SciTech Connect

Septic cavernous sinus thrombosis, a relatively uncommon disease entity, frequently can be fatal. Early diagnosis is imperative in order that appropriate treatment be instituted. A 59-year-old woman who was admitted to our institution with complaints of diplopia, blurred vision and fevers that developed following a tooth extraction is presented. Initial CT and lumbar puncture on the day of admission were totally normal. A repeat CT performed 48 hours after admission, on the same day as gallium imaging, demonstrated findings consistent with cavernous sinus thrombosis. Gallium imaging demonstrated intense uptake in the left cavernous sinus and left orbit as well as moderately increased activity in the right cavernous sinus and orbit, confirming infection. The patient was treated with antibiotics, and repeat CT and gallium imaging were performed ten days later, both of which demonstrated near total resolution of the disease process. Conceivably, if gallium imaging had been initiated on the day of admission it may have been the first study to demonstrate an infectious process in the cavernous sinus. Gallium imaging should be considered as a diagnostic tool in the noninvasive workup of this entity.

Palestro, C.J.; Malat, J.; Gladstone, A.G.; Richman, A.H.

1986-09-01

209

Preliminary Spectroscopic Measurements for a Gallium Electromagnetic (GEM) Thruster  

NASA Technical Reports Server (NTRS)

As a propellant option for electromagnetic thrusters, liquid ,gallium appears to have several advantages relative to other propellants. The merits of using gallium in an electromagnetic thruster (EMT) are discussed and estimates of discharge current levels and mass flow rates yielding efficient operation are given. The gallium atomic weight of 70 predicts high efficiency in the 1500-2000 s specific impulse range, making it ideal for higher-thrust, near-Earth missions. A spatially and temporally broad spectroscopic survey in the 220-520 nm range is used to determine which species are present in the plasma and estimate electron temperature. The spectra show that neutral, singly, and doubly ionized gallium species are present in a 20 J, 1.8 kA (peak) are discharge. With graphite present on the insulator to facilitate breakdown, singly and doubly ionized carbon atoms are also present, and emission is observed from molecular carbon (CZ) radicals. A determination of the electron temperature was attempted using relative emission line data, and while the spatially and temporally averaged, spectra don't fit well to single temperatures, the data and presence of doubly ionized gallium are consistent with distributions in the 1-3 eV range.

Thomas, Robert E.; Burton, Rodney L.; Glumac, Nick G.; Polzin, Kurt A.

2007-01-01

210

Vertical gradient freezing of doped gallium antimonide semiconductor crystals using submerged heater growth and electromagnetic stirring  

NASA Astrophysics Data System (ADS)

An investigation of the melt growth of uniformly doped gallium-antimonide (GaSb) semiconductor crystals as well as other III-V alloy crystals with uniform composition are underway at the US Air Force Research Laboratory at Hanscom Air Force Base by the vertical gradient freeze (VGF) method utilizing a submerged heater. Stirring can be induced in the GaSb melt just above the crystal growth interface by applying a small radial electric current in the liquid together with an axial magnetic field. The transport of any dopant and/or alloy component by the stirring can promote better melt homogeneity and allow for more rapid growth rates before the onset of constitutional supercooling. This paper presents a numerical model for the unsteady transport of a dopant during the VGF process by submerged heater growth with a steady axial magnetic field and a steady radial electric current. As the strength of the electromagnetic (EM) stirring increases, the convective dopant transport increases, the dopant transport in the melt reaches a steady state at an earlier time during growth, and the top of the crystal which has solidified after a steady state has been achieved exhibits axial dopant homogeneity. For crystal growth with stronger EM stirring, the crystal exhibits less radial segregation and the axially homogeneous section of the crystal is longer. Dopant distributions in the crystal and in the melt at several different stages during growth are presented.

Ma, Nancy; Bliss, David F.; Iseler, Gerald W.

2003-11-01

211

Evaluation of the carcinogenicity of gallium arsenide.  

PubMed

Gallium arsenide (GaAs) is an important semiconductor material. In 2-year inhalation studies, GaAs increased the incidence of lung tumors in female rats, but not in male rats or male and female mice. Alveolar proteinosis followed by chronic active inflammation was the predominant non-neoplastic pulmonary findings. IARC classified GaAs as carcinogenic to humans (group 1) based on the assumption that As and Ga ions are bioavailable. The European Chemical Agency Risk Assessment Committee concluded that GaAs should be classified into Carcinogenicity Category 1B (presumed to have carcinogenic potential for humans; ECHA). We evaluate whether these classifications are justified. Physico-chemical properties of GaAs particles and the degree of mechanical treatment are critical in this evaluation. The available data on mode of action (MOA), genotoxicity and bioavailability do not support the contribution of As or Ga ions to the lung tumors in female rats. Most toxicological studies utilized small particles produced by strong mechanical treatment, destroying the crystalline structure. The resulting amorphous GaAs is not relevant to crystalline GaAs at production and processing sites. The likely tumorigenic MOA is lung toxicity related to particulate-induced inflammation and increased proliferation. It is concluded that there is no evidence for a primary carcinogenic effect of GaAs. PMID:23706044

Bomhard, Ernst M; Gelbke, Heinz-Peter; Schenk, Hermann; Williams, Gary M; Cohen, Samuel M

2013-05-01

212

Characterization of semi-insulating gallium arsenide  

NASA Astrophysics Data System (ADS)

The project was established 18 Nov. 1992 to continue for 12 months. Its purpose has been electrical and optical characterization of samples from semi-insulating (SI) melt-grown crystals of gallium arsenide (GaAs). As a further definition of the project's purpose, the primary goal has been to assist NRL in assessing the properties of SI GaAs crystals grown at NRL by the vertical zone melt (VZM) method. A second aspect of this characterization work has involved samples from SI GaAs crystals grown by various commercial vendors including samples of pre-synthesized GaAs evaluated for its suitability as starting 'feedstock' for VZM growth. Measurements made at Western Washington University (WWU) under the terms of this project accord with a Statement of Work provided at the outset. These have included the following: (1) low-field dc electrical transport data for SI GaAs samples, as functions of temperature; (2) near-infrared (NIR) transmittance/absorption spectra of polished slabs, with data concerning the well-known EL2 defect determined from NIR absorption strength and spectral form; and (3) mid-IR data on absorption caused by carbon acceptors in SI GaAs.

Blakemore, John S.

1993-11-01

213

Formation of etch pits during carbon doping of gallium arsenide with carbon tetrachloride by metalorganic vapor-phase epitaxy  

E-print Network

Formation of etch pits during carbon doping of gallium arsenide with carbon tetrachloride-doped gallium arsenide films grown by metalorganic vapor-phase epitaxy. Deposition was carried out at 505­545 °C with gallium arsenide. Both reactions desorb gallium chlorides and reduce the growth rate, but only the latter

Li, Lian

214

Journal of Crystal Growth 310 (2008) 579583 Red shift in the photoluminescence of indium gallium arsenide nitride  

E-print Network

gallium arsenide nitride (InGaAsN) in 1.0 � 10�6 Torr of nitrogen trifluoride (NF3) has been studied-phase epitaxy; B1. Nitrogen trifluoride; B2. Indium gallium arsenide nitride 1. Introduction Indium galliumJournal of Crystal Growth 310 (2008) 579­583 Red shift in the photoluminescence of indium gallium

Hicks, Robert F.

215

The Soviet-American gallium experiment at Baksan  

SciTech Connect

A gallium solar neutrino detector is sensitive to the full range of the solar neutrino spectrum, including the low-energy neutrinos from the fundamental proton-proton fusion reaction. If neutrino oscillations in the solar interior are responsible for the suppressed {sup 8}B flux measured by the Homestake {sup 37}Cl experiment and the Kamiokande water Cherenkov detector, then a comparison of the gallium, chlorine, and water results may make possible a determination of the neutrino mass difference and mixing angle. A 30-ton gallium detector is currently operating in the Baksan laboratory in the Soviet Union, with a ratio of expected solar signal to measured background (during the first one to two {sup 71}Ge half lives) of approximately one. 28 refs.

Abazov, A. I.; Abdurashitov, D. N.; Anosov, O. L.; Danshin, S. N.; Eroshkina, L. A.; Faizov, E. L.; Gavrin, V. N.; Kalikhov, A. V.; Knodel, T. V.; Knyshenko, I. I.; Kornoukhov, V. N.; Mezentseva, S. A.; Mirmov, I. N.; Ostrinsky, A. I.; Petukhov, V. V; Pshukov, A. M.; Revzin, N. Ye; Shikhin, A. A.; Slyusareva, Ye. D.; Timofeyev, P. V.; Veretenkin, E. P.; Vermul, V. M.; Yantz, V. E.; Zakharov, Yu.; Zatsepin, G. T.; Zhandarov, V. I. [AN SSSR, Mosco

1990-01-01

216

Effect of bronchoscopy on localization of gallium-67 citrate  

SciTech Connect

Bronchoscopy, bronchoalveolar lavage (BAL), and 67Ga lung scans are frequently performed for diagnosis or follow-up of patients with sarcoidosis, interstitial pneumonitis, lymphoma, infections, and bronchogenic carcinoma. Because many patients undergo all 3 of these procedures, it is important to determine what effects bronchoscopy and/or BAL may have on gallium imaging. Because 67Ga accumulates in neutrophils at the site of an inflammatory lesion as well as in those circulating in the vascular compartment, it seems reasonable to postulate that bronchoscopy could cause migration of labeled neutrophils into the lung, resulting in false positive gallium scans. To test this hypothesis, we studied 5 patients with varying chronologic relationships of 67Ga injection, gallium scanning, and bronchoscopy with BAL. In all patients, the repeat 67Ga lung scans remained normal or showed no change after bronchoscopy and BAL. We conclude that bronchoscopy with or without BAL does not cause increased 67Ga uptake by the lung.

Phillips, B.A.; Cooper, K.R.; Fratkin, M.J.

1983-03-01

217

Calculation of region of homogeneity of tin-doped gallium arsenide  

SciTech Connect

By the method of quasichemical reactions the authors calculate the region of homogeneity of gallium arsenide doped with tin. They show that the introduction of tin into gallium arsenide leads to narrowing of the low-temperature boundaries of the region of homogeneity of GaAs on the sides of excess Ga and excess As. The results of the calculation agree with the experimental data, showing that doping of gallium arsenide with tin leads to promotion of decomposition of the solid solution of gallium in gallium arsenide.

Morozov, A.N.; Bublik, V.T.; Morozova, O.Yu.

1988-02-01

218

Synthesis and characterization of inorganic-organic hybrid gallium selenides.  

PubMed

Two semiconducting hybrid gallium selenides, [Ga6Se9(C6H14N2)4][H2O] (1) and [C6H14N2][Ga4Se6(C6H14N2)2] (2), were prepared using a solvothermal method in the presence of 1,2-diaminocyclohexane (1,2-DACH). Both materials consist of neutral inorganic layers, in which 1,2-DACH is covalently bonded to gallium. In 1, the organic amine acts as a monodentate and a bidentate ligand, while in 2, bidentate and uncoordinated 1,2-DACH molecules coexist. PMID:25113435

Ewing, Sarah J; Vaqueiro, Paz

2014-09-01

219

Multiplane gallium tomography in assessment of occupational chest diseases  

SciTech Connect

Gallium-67 scintigraphy is helpful in the evaluation of inflammatory, respiratory diseases. Single-photon emission computed tomography (SPECT) provides three-dimensional tomographic reconstruction of radioisotope distribution in the body. The addition of SPECT to gallium-67 scanning in 27 patients demonstrated an improvement in the sensitivity for detecting the presence and extent of interstitial occupational lung disease. This technique may provide earlier detection of parenchymal lung changes than can the chest x-ray and planar scanning in some patients with asbestosis. Findings in six patients with asbestosis are reported.

Cordasco, E.M.; O'Donnell, J.; MacIntyre, W.; Demeter, S.; Gonzalez, L.; Eren, M.; McMahon, W.; Burns, D.; Feiglin, D.H. (Cleveland Clinic Foundation, OH (USA))

1990-01-01

220

Gallium-67 uptake by the thyroid associated with progressive systemic sclerosis  

SciTech Connect

Although thyroidal uptake of gallium-67 has been described in several thyroid disorders, gallium-67 scanning is not commonly used in the evaluation of thyroid disease. Thyroidal gallium-67 uptake has been reported to occur frequently with subacute thyroiditis, anaplastic thyroid carcinoma, and thyroid lymphoma, and occasionally with Hashimoto's thyroiditis and follicular thyroid carcinoma. A patient is described with progressive systemic sclerosis who, while being scanned for possible active pulmonary involvement, was found incidentally to have abnormal gallium-67 uptake only in the thyroid gland. Fine needle aspiration cytology of the thyroid revealed Hashimoto's thyroiditis. Although Hashimoto's thyroiditis occurs with increased frequency in patients with progressive systemic sclerosis, thyroidal uptake of gallium-67 associated with progressive systemic sclerosis has not, to our knowledge, been previously described. Since aggressive thyroid malignancies frequently are imaged by gallium-67 scintigraphy, fine needle aspiration cytology of the thyroid often is essential in the evaluation of thyroidal gallium-67 uptake.

Sjoberg, R.J.; Blue, P.W.; Kidd, G.S.

1989-01-01

221

Method for improving the growth of cadmium telluride on a gallium arsenide substrate  

SciTech Connect

A method for preparing a gallium arsenide substrate, prior to growing a layer of cadmium telluride on a support surface thereof. The preparation includes the steps of cleaning the gallium arsenide substrate and thereafter forming prepatterned shapes on the support surface of the gallium arsenide substrate. The layer of cadmium telluride then grown on the prepared substrate results in dislocation densities of approximately 1{times}10{sup 6}/cm{sup 2} or less. The prepatterned shapes on the support surface of the gallium arsenide substrate are formed by reactive ion etching an original outer surface of the gallium arsenide substrate and into the body of the gallium arsenide substrate to a depth of at least two microns. The prepatterned shapes have the appearance of cylindrical mesas each having a diameter of at lease twelve microns. After the mesas are formed on the support surface of the gallium arsenide substrate, the substrate is again cleaned.

Reno, J.L.

1990-12-31

222

Gallium arsenide processing for gate array logic  

NASA Astrophysics Data System (ADS)

The development of a reliable and reproducible GaAs process was initiated for applications in gate array logic. Gallium Arsenide is an extremely important material for high speed electronic applications in both digital and analog circuits since its electron mobility is 3 to 5 times that of silicon, this allows for faster switching times for devices fabricated with it. Unfortunately GaAs is an extremely difficult material to process with respect to silicon and since it includes the arsenic component GaAs can be quite dangerous (toxic) especially during some heating steps. The first stage of the research was directed at developing a simple process to produce GaAs MESFETs. The MESFET (MEtal Semiconductor Field Effect Transistor) is the most useful, practical and simple active device which can be fabricated in GaAs. It utilizes an ohmic source and drain contact separated by a Schottky gate. The gate width is typically a few microns. Several process steps were required to produce a good working device including ion implantation, photolithography, thermal annealing, and metal deposition. A process was designed to reduce the total number of steps to a minimum so as to reduce possible errors. The first run produced no good devices. The problem occurred during an aluminum etch step while defining the gate contacts. It was found that the chemical etchant attacked the GaAs causing trenching and subsequent severing of the active gate region from the rest of the device. Thus all devices appeared as open circuits. This problem is being corrected and since it was the last step in the process correction should be successful. The second planned stage involves the circuit assembly of the discrete MESFETs into logic gates for test and analysis. Finally the third stage is to incorporate the designed process with the tested circuit in a layout that would produce the gate array as a GaAs integrated circuit.

Cole, Eric D.

1989-09-01

223

Gallium arsenide processing for gate array logic  

NASA Technical Reports Server (NTRS)

The development of a reliable and reproducible GaAs process was initiated for applications in gate array logic. Gallium Arsenide is an extremely important material for high speed electronic applications in both digital and analog circuits since its electron mobility is 3 to 5 times that of silicon, this allows for faster switching times for devices fabricated with it. Unfortunately GaAs is an extremely difficult material to process with respect to silicon and since it includes the arsenic component GaAs can be quite dangerous (toxic) especially during some heating steps. The first stage of the research was directed at developing a simple process to produce GaAs MESFETs. The MESFET (MEtal Semiconductor Field Effect Transistor) is the most useful, practical and simple active device which can be fabricated in GaAs. It utilizes an ohmic source and drain contact separated by a Schottky gate. The gate width is typically a few microns. Several process steps were required to produce a good working device including ion implantation, photolithography, thermal annealing, and metal deposition. A process was designed to reduce the total number of steps to a minimum so as to reduce possible errors. The first run produced no good devices. The problem occurred during an aluminum etch step while defining the gate contacts. It was found that the chemical etchant attacked the GaAs causing trenching and subsequent severing of the active gate region from the rest of the device. Thus all devices appeared as open circuits. This problem is being corrected and since it was the last step in the process correction should be successful. The second planned stage involves the circuit assembly of the discrete MESFETs into logic gates for test and analysis. Finally the third stage is to incorporate the designed process with the tested circuit in a layout that would produce the gate array as a GaAs integrated circuit.

Cole, Eric D.

1989-01-01

224

By Deborah A. Kramer No primary gallium was produced in the United States in consumption were adjusted to reflect full industry coverage.  

E-print Network

was With the exception of 99.999999%-pure gallium, prices for in the form of gallium arsenide (GaAs). Optoelectronic1 GALLIUM By Deborah A. Kramer No primary gallium was produced in the United States in consumption consumers of gallium in the world, its needs were met from imported material. France and Russia were

225

Modified permittivity observed in bulk Gallium Arsenide and Gallium Phosphide samples at 50 K using the Whispering Gallery mode method  

E-print Network

Whispering Gallery modes in bulk cylindrical Gallium Arsenide and Gallium Phosphide samples have been examined both in darkness and under white light at 50 K. In both samples we observed change in permittivity under light and dark conditions. This results from a change in the polarization state of the semiconductor, which is consistent with a free electron-hole creation/recombination process. The permittivity of the semiconductor is modified by free photocarriers in the surface layers of the sample which is the region sampled by Whispering Gallery modes.

Hartnett, J G; Floch, J-M Le; Krupka, J; Tobar, Michael E; Cros, D

2009-01-01

226

Nucleation mechanism of gallium-assisted molecular beam epitaxy growth of gallium arsenide nanowires  

SciTech Connect

Molecular beam epitaxy Ga-assisted synthesis of GaAs nanowires is demonstrated. The nucleation and growth are seen to be related to the presence of a SiO{sub 2} layer previously deposited on the GaAs wafer. The interaction of the reactive gallium with the SiO{sub 2} pinholes induces the formation of nanocraters, found to be the key for the nucleation of the nanowires. With SiO{sub 2} thicknesses up to 30 nm, nanocraters reach the underlying substrate, resulting into a preferential growth orientation of the nanowires. Possibly related to the formation of nanocraters, we observe an incubation period of 258 s before the nanowires growth is initiated.

Fontcuberta i Morral, A.; Colombo, C.; Abstreiter, G.; Arbiol, J.; Morante, J. R. [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, 85748 Garching (Germany); TEM-MAT, Serveis Cientificotecnics, Universitat de Barcelona, CAT, E-08080 Barcelona (Spain); EME/CeRMAE/IN2UB, Departament d'Electronica, Universitat de Barcelona, C/Marti i Franques 1, CAT, E-08080 Barcelona (Spain)

2008-02-11

227

Discovery of Gallium, Germanium, Lutetium, and Hafnium Isotopes  

E-print Network

Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

J. L. Gross; M. Thoennessen

2011-09-28

228

Discovery of gallium, germanium, lutetium, and hafnium isotopes  

SciTech Connect

Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

Gross, J.L.; Thoennessen, M., E-mail: thoennessen@nscl.msu.edu

2012-09-15

229

Structure and vibrational frequencies of aluminum trifluoride and gallium trifluoride  

Microsoft Academic Search

The major features of the EMR-100 electron diffraction camera were given in our previous work [6]. The experimental conditions were given in Table i. A pure-grade sample was used for the aluminum trifluoride exposures. A sample of gallium trifluoride was obtained by treatment of GaF3\\

A. N. Utkin; G. V. Girichev; N. I. Giricheva; S. V. Khaustov

1986-01-01

230

Improved method of fabricating planar gallium arsenide diodes  

NASA Technical Reports Server (NTRS)

Improved method fabricates electroluminescent planar P-N gallium arsenide diodes. GaAs is masked with silicon monoxide to allow P-type impurities to be diffused into unmasked portions of GaAs to form P-N junctions.

Roy, M. M.; Yeh, T. H.

1969-01-01

231

Nanoindentation creep of single-crystal tungsten and gallium arsenide  

Microsoft Academic Search

An extensive study of indentation creep on the nanometre scale has been made on single-crystal indium, tungsten and gallium arsenide. We use the force modulation technique which gives a direct measure of contact stiffness and, being insensitive to thermal drift, allows the accurate observation of creep in small indents to be carried out over long time periods: We show that

S. A. Syed Asif; J. B. Pethica

1997-01-01

232

Terbium gallium garnet Verdet constant measurements with pulsed magnetic field  

Microsoft Academic Search

The dispersion of the Verdet constant of a single-crystal terbium gallium garnet (TGG) was measured using a pulsed magnetic field up to 70 KG. The data show a large Verdet constant for TGG throughout the visible region. The observed hysteresis effect is briefly discussed.

A. B. Villaverde; D. A. Donatti; D. G. Bozinis

1978-01-01

233

Room-temperature inverse Faraday effect in terbium gallium garnet  

Microsoft Academic Search

The inverse Faraday effect (IFE) in terbium gallium garnet (TGG) is observed at room temperature. A circularly polarized 532 nm optical pulse from a frequency doubled Nd:YAG laser traverses a TGG crystal, resulting in an induced voltage in a surrounding detection coil. Variation of laser intensity and polarization direction leads to changes in the induced voltage in accordance with Faraday’s

M. Yasin Akhtar Raja; David Allen; Wade Sisk

1995-01-01

234

On the onset of oscillatory convection in molten gallium  

Microsoft Academic Search

The results of experimental and numerical investigations of the onset of oscillatory convection in a sidewall heated rectangular cavity of molten gallium are reported. Detailed comparisons are made between experimental observations and calculations from numerical simulations of a three-dimensional Boussinesq model. The onset of time-dependence takes place through supercritical Hopf bifurcations and the loci of critical points in the (Gr,

L. Z HAO; D. H ENRY

2004-01-01

235

Formation of Dislocation Networks in Gallium Single Crystals  

Microsoft Academic Search

The development of dislocation networks in gallium crystals, initially free of detectable dislocations, has been studied at room temperature by an x-ray diffraction topographic technique. The condition required for the development of these networks is the existence of spatial periodic fluctuations in impurity content. The networks develop, in the absence of an external stress, from individual loops which are first

S. H. McFarlane III; C. Elbaum

1967-01-01

236

Study of Magnetohydrodynamic Surface Waves on Liquid Gallium  

Microsoft Academic Search

Magnetohydrodynamic (MHD) surface waves on liquid gallium are studied theoretically and experimentally in the small magnetic Reynolds number limit. A linear dispersion relation is derived when a horizontal magnetic field and a horizontal electric current is imposed. No wave damping is found in the shallow liquid limit while waves always damp in the deep liquid limit with a magnetic field

Hantao Ji; William Fox; David Pace; H. L. Rappaport

2004-01-01

237

Induction mechanisms in von Karman swirling flows of liquid gallium  

Microsoft Academic Search

Using in situ magnetic field measurements, we study the induction mechanisms in a swirling flow of liquid Gallium generated inside a cylinder, in the gap between two coaxial rotating discs. The von Karman flow generated in this manner has both helicity and differential rotation. Magnetic Reynolds numbers Rm up to 7 (based on the disc rim speed) are generated. We

M. Bourgoin; R. Volk; P. Frick; S. Khripchenko; Ph. Odier; J.-F. Pinton

2004-01-01

238

Gallium nitrate ameliorates type II collagen-induced arthritis in mice.  

PubMed

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease. Gallium nitrate has been reported to reserve immunosuppressive activities. Therefore, we assessed the therapeutic effects of gallium nitrate in the mouse model of developed type II collagen-induced arthritis (CIA). CIA was induced by bovine type II collagen with Complete Freund's adjuvant. CIA mice were intraperitoneally treated from day 36 to day 49 after immunization with 3.5mg/kg/day, 7mg/kg/day gallium nitrate or vehicle. Gallium nitrate ameliorated the progression of mice with CIA. The clinical symptoms of collagen-induced arthritis did not progress after treatment with gallium nitrate. Gallium nitrate inhibited the increase of CD4(+) T cell populations (p<0.05) and also inhibited the type II collagen-specific IgG2a-isotype autoantibodies (p<0.05). Gallium nitrate reduced the serum levels of TNF-?, IL-6 and IFN-? (p<0.05) and the mRNA expression levels of these cytokine and MMPs (MMP2 and MMP9) in joint tissues. Western blotting of members of the NF-?B signaling pathway revealed that gallium nitrate inhibits the activation of NF-?B by blocking I?B degradation. These data suggest that gallium nitrate is a potential therapeutic agent for autoimmune inflammatory arthritis through its inhibition of the NF-?B pathway, and these results may help to elucidate gallium nitrate-mediated mechanisms of immunosuppression in patients with RA. PMID:24656780

Choi, Jae-Hyeog; Lee, Jong-Hwan; Roh, Kug-Hwan; Seo, Su-Kil; Choi, Il-Whan; Park, Sae-Gwang; Lim, Jun-Goo; Lee, Won-Jin; Kim, Myoung-Hun; Cho, Kwang-rae; Kim, Young-Jae

2014-05-01

239

Pair distribution function study on compression of liquid gallium  

NASA Astrophysics Data System (ADS)

Integrating a hydrothermal diamond anvil cell (HDAC) and focused high energy x-ray beam from the superconductor wiggler X17 beamline at the National Synchrotron Light Source (NSLS) at the Brookhaven National Laboratory (BNL), we have successfully collected high quality total x-ray scattering data of liquid gallium. The experiments were conducted at a pressure range from 0.1GPa up to 2GPa at ambient temperature. For the first time, pair distribution functions (PDF) for liquid gallium at high pressure were derived up to 10 Å. Liquid gallium structure has been studied by x-ray absorption (Di Cicco & Filipponi, 1993; Wei et al., 2000; Comez et al., 2001), x-ray diffraction studies (Waseda & Suzuki, 1972), and molecular dynamics simulation (Tsay, 1993; Hui et al., 2002). These previous reports have focused on the 1st nearest neighbor structure, which tells us little about the atomic arrangement outside the first shell in non- crystalline materials. This study focuses on the structure of liquid gallium and the atomic structure change due to compression. The PDF results show that the observed atomic distance of the first nearest neighbor at 2.78 Å (first G(r) peak and its shoulder at the higher Q position) is consistent with previous studies by x-ray absorption (2.76 Å, Comez et al., 2001). We have also observed that the first nearest neighbor peak position did not change with pressure increasing, while the farther peaks positions in the intermediate distance range decreased with pressure increasing. This leads to a conclusion of the possible existence of "locally rigid units" in the liquid. With the addition of reverse Monte Carlo modeling, we have observed that the coordination number in the local rigit unit increases with pressure. The bulk modulus of liquid gallium derived from the volume compression curve at ambient temperature (300K) is 12.1(6) GPa.

Yu, T.; Ehm, L.; Chen, J.; Guo, Q.; Luo, S.; Parise, J.

2008-12-01

240

Adsorption of primary substituted hydrocarbons onto solid gallium substrates.  

PubMed

Adsorption of a series of primary substituted hydrocarbons (RX; C18H37PO(OH)2 (ODPA), C17H35COOH, C18H37OH, C18H37NH2, and C18H37SH) onto solid gallium substrates with and without UV/ozone treatment was studied using contact angle goniometry, spectroscopic ellipsometry, and cyclic voltammetry (CV). UV/ozone treatment offered a hydrophilic surface (water contact angle (?(water)) less than 10°), reflecting the formation of a surface oxide layer with the maximum thickness of ca. 1 nm and possibly the removal of surface contaminants. Upon immersion in a toluene solution of a RX, ?(water) increased due to adsorption of the RX onto gallium substrates. In particular, UV/ozone-treated gallium substrates (UV-Ga) immersed in an ODPA solution exhibited ?(water) close to 105°. The ellipsometric thickness of the adsorbed ODPA layer was ca. 2.4 nm, and CV data measured in an acetonitrile solution showed significant inhibition of redox reaction on the substrate surface. These results indicate the formation of a densely packed ODPA monolayer on UV-Ga. The coverage of a C17H35COOH layer adsorbed onto UV-Ga was lower, as shown by smaller ?(water) (ca. 99°), smaller ellipsometric thickness (ca. 1.3 nm), and smaller electrode reaction inhibition. Adsorption of the other RX onto UV-Ga was weaker, as indicated by smaller ?(water) (82°-92°). ODPA did not strongly adsorb onto UV-untreated gallium substrates, suggesting that the ODPA adsorption mainly originates from hydrogen bond interaction of a phosphonate group with surface oxide. These results will provide a means for controlling the surface properties of oxide-coated gallium that play an essential role in monolayer conductivity measurements and electroanalytical applications. PMID:23484619

De Silva, Chrishani M; Pandey, Bipin; Li, Feng; Ito, Takashi

2013-04-01

241

Self- and zinc diffusion in gallium antimonide  

SciTech Connect

The technological age has in large part been driven by the applications of semiconductors, and most notably by silicon. Our lives have been thoroughly changed by devices using the broad range of semiconductor technology developed over the past forty years. Much of the technological development has its foundation in research carried out on the different semiconductors whose properties can be exploited to make transistors, lasers, and many other devices. While the technological focus has largely been on silicon, many other semiconductor systems have applications in industry and offer formidable academic challenges. Diffusion studies belong to the most basic studies in semiconductors, important from both an application as well as research standpoint. Diffusion processes govern the junctions formed for device applications. As the device dimensions are decreased and the dopant concentrations increased, keeping pace with Moore's Law, a deeper understanding of diffusion is necessary to establish and maintain the sharp dopant profiles engineered for optimal device performance. From an academic viewpoint, diffusion in semiconductors allows for the study of point defects. Very few techniques exist which allow for the extraction of as much information of their properties. This study focuses on diffusion in the semiconductor gallium antimonide (GaSb). As will become clear, this compound semiconductor proves to be a powerful one for investigating both self- and foreign atom diffusion. While the results have direct applications for work on GaSb devices, the results should also be taken in the broader context of III-V semiconductors. Results here can be compared and contrasted to results in systems such as GaAs and even GaN, indicating trends within this common group of semiconductors. The results also have direct importance for ternary and quaternary semiconductor systems used in devices such as high speed InP/GaAsSb/InP double heterojunction bipolar transistors (DHBT) [Dvorak, (2001)]. Many of the findings which will be reported here were previously published in three journal articles. Hartmut Bracht was the lead author on two articles on self-diffusion studies in GaSb [Bracht, (2001), (2000)], while this report's author was the lead author on Zn diffusion results [Nicols, (2001)]. Much of the information contained herein can be found in those articles, but a more detailed treatment is presented here.

Nicols, Samuel Piers

2002-03-26

242

Investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium crystals by the Czochralski method  

Microsoft Academic Search

Numerical investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium garnet crystals in the same thermal zone and comparison of the obtained results with the experimental data have been performed. It is shown that the difference in the behavior of the crystallization front during growth of the crystals is related to their

O. N. Budenkova; M. G. Vasiliev; V. S. Yuferev; I. A. Ivanov; A. M. Bul'Kanov; V. V. Kalaev

2008-01-01

243

Swift hopping gallium over [AlO4]- tetrahedra in Ga/ZSM-5: A DFT study  

NASA Astrophysics Data System (ADS)

Density functional theory calculations were carried out to investigate gallium species (Ga+, [GaH2]+, and [GaO]+) stabilization in Ga-exchanged HZSM-5, using cluster modeling approach. Three isomeric gallium positions over [AlO4]- zeolite fragment at T12 position were found. These isomers are turning into each over with low activation energy barrier and gallium fragment revolves around [AlO4]- tetrahedron by hopping between cationic positions. Activation energies of gallium fragment hopping were computed and compared for different gallium containing cations. Those barriers were found to be times less than the activation energies of catalytic processes on gallium-exchanged zeolite.0

Kusmin, Ilya V.; Zhidomirov, Georgy M.; Solkan, Vitaly N.

244

Structural study of gallium oxynitrides prepared by ammonolysis of different oxide precursors  

NASA Astrophysics Data System (ADS)

A comparative structural study has been carried out on gallium oxynitride powders using XRD and Raman spectroscopy. Gallium oxynitrides have been prepared by ammonolysis of either NiGa2O4 ternary oxide or the citrate method-derived amorphous oxide. Their crystal chemistry is different and appears to be influenced by the nature of the oxide precursor: whereas gallium oxynitride obtained from amorphous gallium oxide crystallizes with the common wurtzite structure, gallium oxynitride obtained from NiGa2O4 crystallizes with an original structure that we have identified as the carborundum II (B6) structure type or 6H-SiC. As far as we know, this is the first 6H-SiC structure found in gallium oxynitride powders.

Cailleaux, Xavier; de Lucas, María del Carmen Marco; Merdrignac-Conanec, Odile; Tessier, Franck; Nagasaka, Kazuteru; Kikkawa, Shinichi

2009-02-01

245

Developmentof Drug Resistance to Gallium Nitrate through Modulation of Cellular Iron Uptake1  

Microsoft Academic Search

We have shown that transferrin-gallium (Tf-Ga) blocks DNA synthe sis through inhibition of cellular iron incorporation and a diminution in the activity of the iron-dependent M2 subunit of ribonucleotide reductase. To examine the mechanisms of drug resistance to gallium, we developed a subline of HL60 cells (R cells) which is 29-fold more resistant to growth inhibition by gallium nitrate than

Christopher R. Chitambar; Zorica Zivkovic-Gilgenbach; Jana Narasimhan; William E. Antholine

246

Gallium-arsenide deep-level pin tunnel diode with very negative conductance  

E-print Network

Gallium-arsenide deep-level pin tunnel diode with very negative conductance J.L. Pan, J.E. Mc-temperature-grown gallium arsenide (GaAs) are demonstrated. At room temperature, the negative conductance per area of 1) gallium arsenide (GaAs). At room temperature, our NDC per area of 1=1.2 kO mm2 is the largest ever

Woodall, Jerry M.

247

Gallium uptake in the thyroid gland in amiodarone-induced hyperthyroidism  

SciTech Connect

Amiodarone is an iodinated antiarrhythmic agent that is effective in the treatment of atrial and ventricular arrhythmias. A number of side effects are seen, including pulmonary toxicity and thyroid dysfunction. A patient with both amiodarone-induced pneumonitis and hyperthyroidism who exhibited abnormal gallium activity in the lungs, as well as diffuse gallium uptake in the thyroid gland is presented. The latter has not been previously reported and supports the concept of iodide-induced thyroiditis with gallium uptake reflecting the inflammatory response.

Ling, M.C.; Dake, M.D.; Okerlund, M.D.

1988-04-01

248

Magnetotransport and magnetocrystalline anisotropy studies of gallium manganese arsenide thin films.  

E-print Network

??The ferromagnetic semiconductor gallium manganese arsenide is an important test-bed material for spintronics applications. Whilst a Curie temperature anywhere close to room temperature has yet… (more)

King, Christopher Stuart

2008-01-01

249

Critical field and growth rates in a columnar Gallium-Tayler experiment  

E-print Network

The Tayler instability (TI) is experimentally realized in a liquid-metal flow confined in a columnar container with an insulating outer cylinder. To predict the critical electrical current and the expected growth rates, simulations with MHD codes are used for a container with an inner cylinder whose radius is small or even zero. The very small magnetic Prandtl number of the gallium alloy (Pm\\simeq 10^{-6}) only influences the growth rates rather than the critical field amplitudes. It is thus allowed to calculate the critical Hartmann numbers for marginal instability also with direct numerical simulations. The theoretical value of the critical electric current of 2.8 kA, resulting from both linear theory and simulations, is well confirmed by the experiment. Also the predicted (small) growth rates of the nonaxisymmetric kink-type perturbations are certified by the observed data. Due to the rather long growth times of order of minutes, the resulting Joule heating might excite convective modes forming a saturatio...

Ruediger, Guenther; Schultz, Manfred; Strassmeier, Klaus G; Stefani, Frank; Gundrum, Thomas; Seilmayer, Martin; Gerbeth, Gunter

2012-01-01

250

Mechanical Alloying  

Microsoft Academic Search

A new technique of combining metals has been developed which overcomes many of the limitations of conventional alloying. Ball mills that generate higher energies than conventional ball mills are used to tumble a mixture of powders, such as WC and Co, in order to form a composite. Ni-base alloys can be dispersion-hardened in this way with an oxide such as

J. S. Benjamin

1976-01-01

251

Preparation Of Copper Indium Gallium Diselenide Films For Solar Cells  

DOEpatents

High quality thin films of copper-indium-gallium-diselenide useful in the production of solar cells are prepared by electrodepositing at least one of the constituent metals onto a glass/Mo substrate, followed by physical vapor deposition of copper and selenium or indium and selenium to adjust the final stoichiometry of the thin film to approximately Cu(In,Ga)Se.sub.2. Using an AC voltage of 1-100 KHz in combination with a DC voltage for electrodeposition improves the morphology and growth rate of the deposited thin film. An electrodeposition solution comprising at least in part an organic solvent may be used in conjunction with an increased cathodic potential to increase the gallium content of the electrodeposited thin film.

Bhattacharya, Raghu N. (Littleton, CO); Contreras, Miguel A. (Golden, CO); Keane, James (Lakewood, CO); Tennant, Andrew L. (Denver, CO), Tuttle, John R. (Denver, CO); Ramanathan, Kannan (Lakewood, CO); Noufi, Rommel (Golden, CO)

1998-08-08

252

Vapor-Phase Synthesis of Gallium Phosphide Nanowires  

SciTech Connect

Gallium phosphide (GaP) nanowires were synthesized in a high yield by vapor-phase reaction of gallium vapor and phosphorus vapor at 1150 C in a tube furnace system. The nanowires have diameters in the range of 25-100 nm and lengths of up to tens of micrometers. Twinning growth occurs in GaP nanowires, and as a result most nanowires contain a high density of twinning faults. Novel necklacelike GaP nanostructures that were formed by stringing tens of amorphous Ga-P-O microbeads upon one crystalline GaP nanowires were also found in some synthesis runs. This simple vapor-phase approach may be applied to synthesize other important group III-V compound nanowires.

Gu, Dr Zhanjun [University of Georgia, Athens, GA; Paranthaman, Mariappan Parans [ORNL; Pan, Zhengwei [University of Georgia, Athens, GA

2009-01-01

253

Thermal modeling of power gallium arsenide microwave integrated circuits  

SciTech Connect

Low-power Gallium Arsenide-based microwave circuits have been used for many years for frequencies higher than those possible with silicon technology. At the present time manufacturers are developing power devices for ever higher frequencies using GaAs MESFET's and heterojunction bipolar devices constructed with III-V compounds on GaAs substrates. There is also interest in integrating power devices on Monolithic Microwave Integrated Circuits (MMIC's). A problem with the technology is the low thermal conductivity of Gallium Arsenide and this gives rise to thermal design problems which must be solved if good reliability is to be achieved. The paper uses a three-dimensional numerical simulator to study this problem and in particular examines the approximations which are possible in performing realistic assessments of the thermal resistance of typical GaAs power device structures under steady-state conditions.

Webb, P.W. (Univ. of Birmingham, Edgbaston (United Kingdom))

1993-05-01

254

Structure changes in gallium near its melting point  

NASA Astrophysics Data System (ADS)

The electrical resistivity as a function of temperature was measured for gallium samples annealed above the melting point and cooled down to -100°C. The observed phase transition temperatures depend on the temperature of the annealing in the liquid state. The complete phase diagram in (T ann, T cr) coordinates was constructed. Neutron diffraction measurements are consistent with the phase diagram obtained from the electrical resistivity data.

Wolny, J.; Nizio?, S.; ?u?ny, W.; Pytlik, L.; So?tys, J.; Kokoszka, R.

1986-06-01

255

A high open-circuit voltage gallium nitride betavoltaic microbattery  

Microsoft Academic Search

A high open-circuit voltage betavoltaic microbattery based on a gallium nitride (GaN) p–i–n homojunction is demonstrated. As a beta-absorbing layer, the low electron concentration of the n-type GaN layer is achieved by the process of Fe compensation doping. Under the irradiation of a planar solid 63Ni source with activity of 0.5 mCi, the open-circuit voltage of the fabricated microbattery with

Zaijun Cheng; Xuyuan Chen; Haisheng San; Zhihong Feng; Bo Liu

2012-01-01

256

Trap influence on the performance of gallium arsenide radiation detectors  

SciTech Connect

Ohmic contacts play an important role in the performance of LEC gallium arsenide particle detectors since they possibly control the injection of charge carriers. Contact characteristics have been compared and related to electrically active defects induced during contact preparation and to the detector efficiency. The electric field distribution has also been analyzed. Spectroscopic investigations have put into evidence that the contact fabrication process significantly influences the trap density whilst it does not change their signatures.

Castaldini, A.; Cavallini, A.; Polenta, L. [Univ. of Bologna (Italy); Canali, C.; Nava, F. [Univ. of Modena (Italy); Papa, C. del [Univ. of Udine (Italy). Dept. of Physics

1996-12-31

257

Observation of dark dot splitting pattern in terbium gallium garnet  

Microsoft Academic Search

.   We have observed a new polarisation pattern in terbium gallium garnet which is both laser excited and mechanically stressed.\\u000a The pattern can be characterized by a splitting from a “one dot” structure to a “two dots” structure. We have found that the\\u000a new pattern is very sensitive to the orientation and the strength of the external forces applied to

X. Chen; A. Savary

1999-01-01

258

Terahertz Cherenkov radiation from ultrafast magnetization in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

We report an experimental observation of terahertz Cherenkov radiation from a moving magnetic moment produced in terbium gallium garnet by a circularly polarized femtosecond laser pulse via the inverse Faraday effect. Contrary to some existing theoretical predictions, the polarity of the observed radiation unambiguously demonstrates the paramagnetic, rather than diamagnetic, nature of the ultrafast inverse Faraday effect. From measurements of the radiation field, the Verdet constant in the subpicosecond regime is ˜3-10 times smaller than its table quasistatic value.

Gorelov, S. D.; Mashkovich, E. A.; Tsarev, M. V.; Bakunov, M. I.

2013-12-01

259

Observation of dark dot splitting pattern in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

We have observed a new polarisation pattern in terbium gallium garnet which is both laser excited and mechanically stressed. The pattern can be characterized by a splitting from a ``one dot'' structure to a ``two dots'' structure. We have found that the new pattern is very sensitive to the orientation and the strength of the external forces applied to the sample. Thanks to this sensitivity and to the image simplicity, this new effect may be used in a vectorial force sensor and actuator.

Chen, X.

260

Room-temperature inverse Faraday effect in terbium gallium garnet  

NASA Astrophysics Data System (ADS)

The inverse Faraday effect (IFE) in terbium gallium garnet (TGG) is observed at room temperature. A circularly polarized 532 nm optical pulse from a frequency doubled Nd:YAG laser traverses a TGG crystal, resulting in an induced voltage in a surrounding detection coil. Variation of laser intensity and polarization direction leads to changes in the induced voltage in accordance with Faraday's law of induction. The IFE is attributed to the optical Stark effect.

Raja, M. Yasin Akhtar; Allen, David; Sisk, Wade

1995-10-01

261

Low-temperature thermal conductivity of terbium-gallium garnet  

Microsoft Academic Search

Thermal conductivity of paramagnetic Tb3Ga5O12 (TbGG) terbium-gallium garnet single crystals is investigated at temperatures from 0.4 to 300 K in magnetic fields up to\\u000a 3.25 T. A minimum is observed in the temperature dependence ?(T) of thermal conductivity at T\\u000a min = 0.52 K. This and other singularities on the ?(T) dependence are associated with scattering of phonons from terbium

A. V. Inyushkin; A. N. Taldenkov

2010-01-01

262

Properties of gallium phosphide films prepared by rf magnetron sputtering  

Microsoft Academic Search

As a coating material with excellent durability in 8 - 12 micrometers waveband, GaP films can be used as anti-reflective and protective layers on the windows and domes of ZnS, ZnSe and Ge. In this paper GaP films have been deposited by radio frequency magnetron sputtering of single crystalline gallium phosphide. The deposition rate, composition, structure, hardness and optical properties

Jianquan Song; Zhengtang Liu; Dagang Guo; Zhongqi Yu; Dongsheng Geng; Xiulin Zheng

2000-01-01

263

Appraisal of lupus nephritis by renal imaging with gallium-67  

SciTech Connect

To assess the activity of lupus nephritis, 43 patients with systemic lupus erythematosus (SLE) were studied by gallium imaging. Delayed renal visualization 48 hours after the gallium injection, a positive result, was noted in 25 of 48 scans. Active renal disease was defined by the presence of hematuria, pyuria (10 or more red blood cells or white blood cells per high-power field), proteinuria (1 g or more per 24 hours), a rising serum creatinine level, or a recent biopsy specimen showing proliferative and/or necrotizing lesions involving more than 20 percent of glomeruli. Renal disease was active in 18 instances, inactive in 23, and undetermined in seven (a total of 48 scans). Sixteen of the 18 scans (89 percent) in patients with active renal disease showed positive findings, as compared with only four of 23 scans (17 percent) in patients with inactive renal disease (p less than 0.001). Patients with positive scanning results had a higher rate of hypertension (p = 0.02), nephrotic proteinuria (p = 0.01), and progressive renal failure (p = 0.02). Mild mesangial nephritis (World Health Organization classes I and II) was noted only in the patients with negative scanning results (p = 0.02) who, however, showed a higher incidence of severe extrarenal SLE (p = 0.04). It is concluded that gallium imaging is a useful tool in evaluating the activity of lupus nephritis.

Bakir, A.A.; Lopez-Majano, V.; Hryhorczuk, D.O.; Rhee, H.L.; Dunea, G.

1985-08-01

264

Evaluation of the male reproductive toxicity of gallium arsenide.  

PubMed

Gallium arsenide is an important semiconductor material marketed in the shape of wafers and thus is not hazardous to the end user. Exposure to GaAs particles may, however, occur during manufacture and processing. Potential hazards require evaluation. In 14-week inhalation studies with small GaAs particles, testicular effects have been reported in rats and mice. These effects occurred only in animals whose lungs showed marked inflammation and also had hematologic changes indicating anemia and hemolysis. The time- and concentration-dependent progressive nature of the lung and blood effects together with bioavailability data on gallium and arsenic lead us to conclude that the testicular/sperm effects are secondary to hypoxemia resulting from lung damage rather than due to a direct chemical effect of gallium or arsenide. Conditions leading to such primary effects are not expected to occur in humans at production and processing sites. This has to be taken into consideration for any classification decision for reproductive toxicity; especially a category 1 according to the EU CLP system is not warranted. PMID:22728686

Bomhard, Ernst M; Cohen, Samuel M; Gelbke, Heinz-Peter; Williams, Gary M

2012-10-01

265

Thermodynamics of Ca-Ga alloys  

SciTech Connect

The enthalpies of formation of the intermetallic compounds CaGa{sub 4}, Ca{sub 3}Ga{sub 8}, and CaGa{sub 2}, at 298.15 K, were determined by high-temperature liquid gallium solution calorimetric measurements to be {minus}24.9 {+-} 4.9 kJ{center_dot}g at.{sup {minus}1}, {minus}25.4 {+-} 2.4 kJ{center_dot}g at.{sup {minus}1}, and {minus}38.8 {+-} 4.8 kJ{center_dot}g at.{sup {minus}1}, respectively. The integral enthalpy of mixing of the (Ca-Ga) liquid alloys ({Delta}H{sup 0}) measured at 1309 K are described by the following Redlich-Kister equation: ({Delta}H{sup 0}) = x{sub Ca} (1 {minus} x{sub Ca}) f(y) with f(y) = 48.00y{sup 2} {minus} 9.34y {minus} 161.16 and y = x{sub Ca} {minus} x{sub Ga}. The partial enthalpy of calcium in gallium at infinite dilution ({Delta}(bar H){sub Ca}{sup 0}), deduced from the measured integral enthalpies of mixing at 1309 K, is {minus}104.8 {+-} 1.7 kJ{center_dot}g at.{sup {minus}1}, which is in very good agreement with that derived from the gallium solution calorimetric measurements at 1074 K ({minus}108.2 {+-} 6.9 kJ{center_dot}g at.{sup {minus}1}).

Prabhakara Reddy, B.; Babu, R.; Nagarajan, K.; Vasudeva Rao, P.R. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Dept. of Atomic Energy

1999-06-01

266

Comparison of the antimicrobial activities of gallium nitrate and gallium maltolate against Mycobacterium avium subsp. paratuberculosis in vitro.  

PubMed

Johne's disease (JD) is an enteric infection of cattle and other ruminants caused by Mycobacterium avium subsp. paratuberculosis (MAP). This study compared the antimicrobial activities of gallium nitrate (GaN) and gallium maltolate (GaM) against two field MAP isolates by use of broth culture. The concentrations that resulted in 99% growth inhibition of isolates 1 and 2 were, respectively, 636?µM and 183?µM for GaN, and 251?µM and 142?µM for GaM. For both isolates, time to detection was significantly higher for GaM than GaN. These results suggest that GaM is more efficient than GaN in inhibiting MAP growth in vitro. PMID:25155307

Fecteau, Marie-Eve; Aceto, Helen W; Bernstein, Lawrence R; Sweeney, Raymond W

2014-10-01

267

Properties of Closed-Shell Titanium Silicate and Gallium-Containing Semiconductor Systems  

NASA Astrophysics Data System (ADS)

We demonstrate that an atomic-scale approach may be appropriate for the analysis of the compositional and bonding properties of titanium silicate alloys and shallow d-core level reflectance spectra of gallium-compound semiconductors. Ti silicate analysis was conducted using X-Ray Absorption Spectroscopy (XAS), X-Ray Photoemission Spectroscopy (XPS), and Spectroscopic Ellipsometry (SE) data taken on a range of Ti-silicate alloys. XAS data were obtained by the Lucovsky group at Stanford Synchrotron Radiation Laboratories (SSRL) at the Stanford Linear Accelerator Center (SLAC), and were used as the primary source of information. To bolster conclusions we solicited XPS data from the Opila Laboratory at the University of Delaware, which were provided by Les Fleming. We also took SE data on Ti silicate alloys annealed at different temperatures using two ellipsometers, one of which was built by the author specifically to probe energies in the vacuum uv range. Reflectance data from 20 to 25 eV, which contain spectral features due to transitions from Ga3d core levels, were obtained on GaP, GaAs, GaSb, GaSe, and GaPxAs1ƒ{x at the storage ring Tantalus 1 at the Stoughton Synchrotron Radiation Center by Aspnes and co-workers from about 1980 to 1982. Ti L2,3 XAS data were fitted with reference spectra to obtain 4-fold coordination concentrations (in differing symmetries) and 6-fold coordination concentrations with respect to alloy composition and annealing. Analyzing the concentrations allowed us to draw conclusions on coordination with respect to alloy composition and annealing. We were able to model the 4-fold ¡§in solution¡¨ to 6-fold phase-segregated conversion as a stochastic process, and we found a complete conversion to 6-fold phase-segregated TiO 2 through annealing with at least 36% Ti and above. We attributed this phase segregation to a striation effect previously reported in the literature. XAS OK1 spectra corroborate these results. Investigation of the XPS Ti L 2,3 data verified the formal Ti valence in the Ti silicate alloys as +4. Through atomic-multiplet calculations, we show that because of Coulombic and spin orbit effects the final states of the Ti L2,3 spectra do not maintain any significant degeneracy, even in the absence of a crystal field. Dielectric functions from 1.5 to 9.0 eV, extracted from the SE data obtained on annealed Ti silicate alloys, verified that significant coordination change occurred between the annealing temperature of 500 and 700 °C. A local atomic multiplet theory was applied to investigate the Ga3d shallow core-level spectra of GaP, GaAs, GaSb, GaSe, and GaAs1-xP x. This is a novel application of an existing theory that is typically used for higher-energy transitions. We modeled these spectra quantitatively as a Ga+3 closed-shell ion affected by perturbations on 3d hole-4p electron final states, specifically spin-orbit effects on the hole and electron, and a crystal-field effect on the hole. The crystal-field perturbation arises from the surrounding bond charges and positive ligand anions. Radial-strength parameters were obtained through a least-squares process, and general trends identified with respect to anion electronegativity. Primary conclusion drawn is that the crystal-field effect, in addition to the spin-orbit interaction, plays a significant role in breaking d-level degeneracy, and consequently is necessary to understand shallow 3d core level spectra.

Stoute, Nicholas Aaron

268

Elastic properties of crystalline and liquid gallium at high pressures  

SciTech Connect

The elastic properties of gallium, such as the bulk modulus B, the shear modulus G, and the Poisson's ratio {sigma}, are investigated and the relative change in the volume is determined in the stability regions of the Ga I, Ga II, and liquid phases at pressures of up to 1.7 GPa. The observed lines of the Ga I-Ga II phase transition and the melting curves of the Ga I and Ga II phases are in good agreement with the known phase diagram of gallium; in this case, the coordinates of the Ga I-Ga II-melt triple point are determined to be 1.24 {+-} 0.40 GPa and 277 {+-} 2 K. It is shown that the Ga I-Ga II phase transition is accompanied by a considerable decrease in the moduli B (by 30%) and G (by 55%) and an increase in the density by 5.7%. The Poisson's ratio exhibits a jump from typically covalent values of approximately 0.22-0.25 to values of approximately 0.32-0.33, which are characteristic of metals. The observed behavior of the elastic characteristics is described in the framework of the model of the phase transition from a 'quasi-molecular' (partially covalent) metal state to a 'normal' metal state. An increase in the Poisson's ratio in the Ga I phase from 0.22 to 0.25 with an increase in the pressure can be interpreted as a decrease in the degree of covalence, i.e., the degree of spatial anisotropy of the electron density along the bonds, whereas the large value of the pressure derivative of the bulk modulus (equal to approximately 8) observed up to the transition to the Ga II phase or the melt is associated not only with the quasicovalent nature of the Ga I phase but also with the structural features. In view of the presence of seven neighbors for each gallium atom in the Ga I phase, the gallium lattice can be treated as a structure intermediate between typical open-packed and close-packed structures. Premelting effects, such as a flattening of the isothermal dependence of the shear modulus G(p) with increasing pressure and an increase in the slope of the isobaric dependences G(T) with increasing temperature, are revealed in the vicinity of the melting curve. The bulk modulus of liquid gallium near the melting curve proves to be rather close to the corresponding values for the normal metal Ga II.

Lyapin, A. G.; Gromnitskaya, E. L.; Yagafarov, O. F., E-mail: oscar.yagafarov@gmail.com; Stal'gorova, O. V.; Brazhkin, V. V. [Russian Academy of Sciences, Institute for High-Pressure Physics (Russian Federation)

2008-11-15

269

Coherent near infrared photodetection with indium gallium arsenide based optoelectronic devices  

NASA Astrophysics Data System (ADS)

Over the extremely broad electromagnetic spectrum, the near-infrared region (0.7--3 mum) is of great interests to physicists, chemists and biologists. Coherent photo-detection in the near-infrared as well as visible and other wavelength regions is extremely useful in identifying coherent light sources from the noisy background. It has great potential to be applied to single-molecule detection by surface-enhanced coherent anti-Stokes Raman scattering. Other applications include chemical gas detection, remote sensing and environmental monitoring, semiconductor processing control and others. Indium gallium arsenide (InGaAs) based optoelectronic devices have been extensively investigated in the wavelength range extending from 800nm for gallium-rich material to 3mum for indium-rich material. A range of InGaAs alloys with bandgap energies in the near infrared wavelength range are investigated by solid-source molecular beam epitaxy (SSMBE). They include strain-free standard In0.532Ga0.468As and In0.532Ga0.468 AsNxSby lattice-matched to InP substrates, highly strained pseudomorphic InxGa1-xAs/InyGa 1-yAs quantum structures on InP substrates and relaxed metamorphic thick Inx>0.8Ga1-xAs device layers with cyclic arsenic-assisted in-situ annealed step-graded InAlAs buffer layers on GaAs and InP substrates. An InP/InAlAs/InGaAs heterojunction bipolar phototransistor (HPT) is designed, simulated and fabricated. The electrical and optical properties, such as responsivity and spectral response, of the HPT are characterized. A compact standing-wave Fourier-transform interferometer system capable of coherent detection in the near-infrared region is demonstrated. A new technique of identifying coherent light sources using harmonic Fourier spectra analysis is developed. The system only includes a PZT-controlled gold-coated scan mirror and a partial-transparent (3.8% single-path loss) InP/InAlAs/InGaAs HPT. The close-loop scan range of PZT-controlled mirror is 32mum. With such mirror scan length, at the harmonic 5th order spectrum components, the resolution of the demonstrated interferometer is 37.5cm-1 with the free spectral range ˜340nm and central spectral position at 1500nm. The system resolution could reach 1 cm-1 with improved system design and elements selection.

Fu, Jun-Xian

270

Thermal and nonthermal melting of gallium arsenide after femtosecond laser excitation K. Sokolowski-Tinten, J. Bialkowski, and M. Boing  

E-print Network

Thermal and nonthermal melting of gallium arsenide after femtosecond laser excitation K. Sokolowski extensively studied during the past decade. Time resolved optical experiments on silicon,1­3 gallium arsenide of femtosecond laser induced melting in gallium arsenide, emphasizing the fluence dependence of the phase

von der Linde, D.

271

Journal of Engineering Physics and Thermophysics, VoL 71, No..5, 1998 SIMULATION OF A GALLIUM ARSENIDE RUNNING  

E-print Network

, and V. A. Sizyuk UDC 621.382 Process of transfer of electrons in a gallium arsenide running. Such structures in the most cases are planar wave-conducting devices on gallium arsenide with a deceleratingJournal of Engineering Physics and Thermophysics, VoL 71, No..5, 1998 SIMULATION OF A GALLIUM

Harilal, S. S.

272

Reflectance-difference spectroscopy of mixed arsenic-rich phases of gallium arsenide ,,001... M. J. Begarney,1  

E-print Network

Reflectance-difference spectroscopy of mixed arsenic-rich phases of gallium arsenide ,,001... M. J on the reflectance difference spec- tra of a series of gallium arsenide 001 reconstructions at arsenic coverages. At the same time, gallium atoms are liberated to the surface, disrupting the c(4 4) ordering. At about 1.4 ML

Li, Lian

273

Gallium-arsenide deep-level tunnel diode with record negative conductance and record peak current density  

E-print Network

Gallium-arsenide deep-level tunnel diode with record negative conductance and record peak current deep-levels in low-temperature-grown (LTG) gallium-arsenide (GaAs) are demonstrated. These tunnel-temperature-grown (LTG) gallium-arsenide (GaAs) gave rise to tunnel diodes having very negative conductance and large

Woodall, Jerry M.

274

Structure and composition of the c,,4 4... reconstruction formed during gallium arsenide metalorganic vapor-phase epitaxy  

E-print Network

Structure and composition of the c,,4 4... reconstruction formed during gallium arsenide-energy electron diffraction. Upon removal from the reactor, the gallium arsenide surface exhibits a (1 2 of Physics. S0003-6951 98 04125-4 The structure of gallium arsenide surfaces present during metalorganic

Li, Lian

275

Saturated Buffer FET Logic for Gallium Arsenide Digital Circuits A.E. Parker & D.J. Skellern.  

E-print Network

Saturated Buffer FET Logic for Gallium Arsenide Digital Circuits A.E. Parker & D.J. Skellern Logic (SBFL) is a new logic family developed for use in Gallium Arsenide digital integrated circuits) inverter circuit is shown in figure 1. This circuit is designed for use in Gallium Arsenide digital

276

Effect of the overheating of the gallium melt on its supercooling during solidification  

NASA Astrophysics Data System (ADS)

The effect of overheating ? T {/L +} of the gallium melt on its supercooling ? T {/L -} during solidification is studied by cyclic thermographic analysis. The obtained data on ? T {/L -} are used to calculate the thermodynamic and kinetic characteristics of gallium solidification.

Aleksandrov, V. D.; Frolova, S. A.

2014-01-01

277

Preliminary survey report: control technology for gallium arsenide processing at Morgan Semiconductor Division, Garland, Texas  

SciTech Connect

The report covers a walk through survey made of the Morgan Semiconductor Facility in Garland, Texas, to evaluate control technology for gallium-arsenide dust in the semiconductor industry. Engineering controls included the synthesis of gallium-arsenide outside the crystal pullers to reduce arsenic residues in the pullers, also reducing worker exposure to arsenic during cleaning of the crystal pullers.

Lenihan, K.L.

1987-03-01

278

Study of Magnetorotational Instability and MHD Surface Waves in Liquid Gallium  

Microsoft Academic Search

Two liquid gallium experiments have been constructed in PPPL to study basic MHD physics related to astrophysics and fusion sciences. The first experiment focuses on laboratory studies of the magnetorotational instability (MRI) in a rotating gallium disk or a short Couette flow geometry. The MRI has been proposed as a dominant mechanism for fast angular momentum transport in electrically-conducting accretion

H. Ji; F. Chen; A. Kageyama; J. Goodman; E. Shoshan; H. Rappaport; M. Borg; J. Halcrow

2002-01-01

279

Low temperature recombination and trapping analysis in high purity gallium arsenide by microwave photodielectric techniques  

NASA Technical Reports Server (NTRS)

Some physical theories pertinent to the measurement properties of gallium arsenide are presented and experimental data are analyzed. A model for explaining recombination and trapping high purity gallium arsenide, valid below 77 K is assembled from points made at various places and an appraisal is given of photodielectric techniques for material property studies.

Khambaty, M. B.; Hartwig, W. H.

1972-01-01

280

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells  

E-print Network

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells O. Lundberga,*, J. Lua , A Abstract The diffusion of indium and gallium in polycrystalline thin film Cu(In,Ga)Se2 layers has been with energy dispersive X-ray spectroscopy. It was found that the grain boundary diffusion

Rockett, Angus

281

By Deborah A. Kramer No gallium production was reported in the McDonnell Douglas Corp. reportedly will world producers were Australia, Germany, and  

E-print Network

was used in research Germany. and development and other applications. Gallium arsenide (GaAs) manufacturers1 GALLIUM By Deborah A. Kramer No gallium production was reported in the McDonnell Douglas Corp. reportedly will world producers were Australia, Germany, and United States in 1994. The U.S. gallium

282

Investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium crystals by the Czochralski method  

NASA Astrophysics Data System (ADS)

Numerical investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium garnet crystals in the same thermal zone and comparison of the obtained results with the experimental data have been performed. It is shown that the difference in the behavior of the crystallization front during growth of the crystals is related to their different transparency in the IR region. In gadolinium gallium garnet crystals, which are transparent to thermal radiation, a crystallization front, strongly convex toward the melt, is formed in the growth stage, which extremely rapidly melts under forced convection. Numerical analysis of this process has been performed within the quasistationary and nonstationary models. At the same time, in terbium gallium garnet crystals, which are characterized by strong absorption of thermal radiation, the phase boundary shape changes fairly smoothly and with a small amplitude. In this case, as the crystal is pulled, the crystallization front tends to become convex toward the crystal bulk.

Budenkova, O. N.; Vasiliev, M. G.; Yuferev, V. S.; Ivanov, I. A.; Bul'Kanov, A. M.; Kalaev, V. V.

2008-12-01

283

Investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium crystals by the Czochralski method  

SciTech Connect

Numerical investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium garnet crystals in the same thermal zone and comparison of the obtained results with the experimental data have been performed. It is shown that the difference in the behavior of the crystallization front during growth of the crystals is related to their different transparency in the IR region. In gadolinium gallium garnet crystals, which are transparent to thermal radiation, a crystallization front, strongly convex toward the melt, is formed in the growth stage, which extremely rapidly melts under forced convection. Numerical analysis of this process has been performed within the quasistationary and nonstationary models. At the same time, in terbium gallium garnet crystals, which are characterized by strong absorption of thermal radiation, the phase boundary shape changes fairly smoothly and with a small amplitude. In this case, as the crystal is pulled, the crystallization front tends to become convex toward the crystal bulk.

Budenkova, O. N., E-mail: olganb@mail.ioffe.ru; Vasiliev, M. G.; Yuferev, V. S. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Ivanov, I. A.; Bul'kanov, A. M. [ZAO Research Institute of Materials Science (Russian Federation); Kalaev, V. V. [OOO Soft Impakt (Russian Federation)

2008-12-15

284

Observation of persistent photoconductivity in bulk Gallium Arsenide and Gallium Phosphide samples at cryogenic temperatures using the Whispering Gallery mode method  

E-print Network

Whispering Gallery modes in bulk cylindrical Gallium Arsenide and Gallium Phosphide samples have been examined both in darkness and under white light at cryogenics temperatures < 50 K. In both cases persistent photoconductivity was observed after initially exposing semiconductors to white light from a halogen lamp. Photoconductance decay time constants for GaP and GaAs were determined to be 0.900 +/- 0.081 ns and 1.098 +/- 0.063 ns, respectively, using this method.

Hartnett, J G; Floch, J -M Le; Krupka, J; Tobar, M E; Cros, D

2009-01-01

285

Investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium gallium crystals by the Czochralski method  

Microsoft Academic Search

Numerical investigation of the variations in the crystallization front shape during growth of gadolinium gallium and terbium\\u000a gallium garnet crystals in the same thermal zone and comparison of the obtained results with the experimental data have been\\u000a performed. It is shown that the difference in the behavior of the crystallization front during growth of the crystals is related\\u000a to their

O. N. Budenkova; M. G. Vasiliev; V. S. Yuferev; I. A. Ivanov; A. M. Bul’kanov; V. V. Kalaev

2008-01-01

286

Superconductivity in gallium-substituted Ba8Si46 clathrates  

E-print Network

Superconductivity in gallium-substituted Ba8Si46 clathrates Yang Li,1,2,3,* Ruihong Zhang,1 Yang Liu,1 Ning Chen,1 Z. P. Luo,4 Xingqiao Ma,1 Guohui Cao,1 Z. S. Feng,5 Chia-Ren Hu,3 and Joseph H. Ross, Jr.3,* 1Department of Physics, University.... ACKNOWLEDGMENTS This work was supported in part by the National Natural Science Foundation of China #1;Grant No. 50372005#2;, the Robert A. Welch Foundation #1;Grant No. A-1526#2;, the UPRM-CID seed program #1;Grant No. SM-07-14#2;, and the National Science...

Li, Yang; Zhang, Ruihong; Liu, Yang; Chen, Ning; Luo, Z. P.; Ma, Xingqiao; Cao, Guohui; Feng, Z. S.; Hu, Chia-Ren; Ross, Joseph H., Jr.

2007-01-01

287

A gallium phosphide high-temperature bipolar junction transistor  

NASA Technical Reports Server (NTRS)

Preliminary results are reported on the development of a high temperature (350 C) gallium phosphide bipolar junction transistor (BJT) for geothermal and other energy applications. This four-layer p(+)n(-)pp(+) structure was formed by liquid phase epitaxy using a supercooling technique to insure uniform nucleation of the thin layers. Magnesium was used as the p-type dopant to avoid excessive out-diffusion into the lightly doped base. By appropriate choice of electrodes, the device may also be driven as an n-channel junction field-effect transistor. The initial design suffers from a series resistance problem which limits the transistor's usefulness at high temperatures.

Zipperian, T. E.; Dawson, L. R.; Chaffin, R. J.

1981-01-01

288

Dielectric response and magnetoelectric coupling in single crystal gallium ferrite  

NASA Astrophysics Data System (ADS)

Here we report the dielectric response and electric conduction behavior of magnetoelectric gallium ferrite single crystals studied using impedance analysis in time and temperature domain. The material exhibits two distinct relaxation processes: a high frequency bulk response and a low frequency interfacial boundary layer response. Calculated bulk capacitance as a function of temperature showed an anomaly at ferri- to paramagnetic transition temperature (˜ 300 K), suggestive of magneto-dielectric coupling in the material. Interestingly, we also witness an abrupt change in the activation energy at ˜ 220 K, in the vicinity of spin-glass transition temperature in GaFeO3.

Mukherjee, Somdutta; Gupta, Rajeev; Garg, Ashish

2013-05-01

289

Lasing action in gallium nitride quasicrystal nanorod arrays.  

PubMed

We report the observation of lasing action from an optically pumped gallium nitride quasicrystal nanorod arrays. The nanorods were fabricated from a GaN substrate by patterned etching, followed by epitaxial regrowth. The nanorods were arranged in a 12-fold symmetric quasicrystal pattern. The regrowth grew hexagonal crystalline facets and core-shell multiple quantum wells (MQWs) on nanorods. Under optical pumping, multiple lasing peaks resembling random lasing were observed. The lasing was identified to be from the emission of MQWs on the nanorod sidewalls. The resonant spectrum and mode field of the 12-fold symmetric photonic quasicrystal nanorod arrays is discussed. PMID:22714233

Chang, Shih-Pang; Sou, Kuok-Pan; Chen, Chieh-Han; Cheng, Yuh-Jen; Huang, Ji-Kai; Lin, Chung-Hsiang; Kuo, Hao-Chung; Chang, Chun-Yen; Hsieh, Wen-Feng

2012-05-21

290

Electron density study of spinels: Magnesium gallium oxide  

Microsoft Academic Search

The electron density distribution in magnesium gallium oxide spinel [composition MgGa2O4; for the general formula TX2O4, tetrahedral site T = MgxGa1 ? x, octahedral site X = Ga1 + xMg1 ? x; x = 0.183(4)] has been studied with single-crystal X-ray diffraction methods through scattering factor refinement procedures. A residual 0.95e\\/Å3 height in harmonic refinement (0.75e\\/Å3 for anharmonic) is situated

H. Sawada

1996-01-01

291

Mode pattern analysis of gallium nitride-based laser diodes  

NASA Astrophysics Data System (ADS)

In this paper, we present an analysis of gallium nitride (GaN) quantum-well (QW) laser diode (LD) by numerical simulation. Here we discuss three aspects that are crucial to our analysis. First, the transverse mode pattern is studied, and our current GaN diode laser structure is discussed with optical waveguide mode analysis. Then we compare the QW design of the laser and maximize laser modal gain. Finally, we report the influence of the electron block (e-block) layer on lasing performance of our design.

Jin, Xiaomin; Jobe, Sean; Trieu, Simeon; Husain, Benafsh; Flickinger, Jason; Zhang, Bei; Dai, Tao; Kang, Xiang-Ning; Zhang, Guo-Yi

2009-07-01

292

Improved performance design of gallium arsenide solar cells for space  

NASA Technical Reports Server (NTRS)

An improved design, shallow junction heteroface, n-p, gallium arsenide solar cell for space applications is reported, with a predicted AM0 efficiency in the 21.9 to 23.0 percent range. The optimized n-p structure, while slightly more efficient, has the added advantage of being less susceptible to radiation-induced degradation by virtue of this thin top junction layer. Detailed spectral response curves and an analysis of the loss mechanisms are reported. The details of the design are readily measurable. The optimized designs were reached by quantifying the dominant loss mechanisms and then minimizing them by using computer simulations.

Parekh, R. H.; Barnett, A. M.

1984-01-01

293

Testing of gallium arsenide solar cells on the CRRES vehicle  

NASA Technical Reports Server (NTRS)

A flight experiment was designed to determine the optimum design for gallium arsenide (GaAs) solar cell panels in a radiation environment. Elements of the experiment design include, different coverglass material and thicknesses, welded and soldered interconnects, different solar cell efficiencies, different solar cell types, and measurement of annealing properties. This experiment is scheduled to fly on the Combined Release and Radiation Effects Satellite (CRRES). This satellite will simultaneously measure the radiation environment and provide engineering data on solar cell degradation that can be directly related to radiation damage.

Trumble, T. M.

1985-01-01

294

Gallium uptake in tryptophan-related pulmonary disease  

SciTech Connect

We describe a patient who developed fever, fatigue, muscle weakness, dyspnea, skin rash, and eosinophilia after taking high doses of tryptophan for insomnia for two years. A gallium-67 scan revealed diffuse increased uptake in the lung and no abnormal uptake in the muscular distribution. Bronchoscopy and biopsy confirmed inflammatory reactions with infiltration by eosinophils, mast cells, and lymphocytes. CT scan showed an interstitial alveolar pattern without fibrosis. EMG demonstrated diffuse myopathy. Muscle biopsy from the right thigh showed an inflammatory myositis with eosinophilic and lymphocytic infiltrations.

Kim, S.M.; Park, C.H.; Intenzo, C.M.; Patel, R. (Thomas Jefferson Univ. Hospital, Philadelphia, PA (USA))

1991-02-01

295

Properties of gallium phosphide films prepared by rf magnetron sputtering  

NASA Astrophysics Data System (ADS)

As a coating material with excellent durability in 8 - 12 micrometers waveband, GaP films can be used as anti-reflective and protective layers on the windows and domes of ZnS, ZnSe and Ge. In this paper GaP films have been deposited by radio frequency magnetron sputtering of single crystalline gallium phosphide. The deposition rate, composition, structure, hardness and optical properties of GaP films have been investigated, and it's application used as anti-reflective and protective films on ZnS substrate has also been studied.

Song, Jianquan; Liu, Zhengtang; Guo, Dagang; Yu, Zhongqi; Geng, Dongsheng; Zheng, Xiulin

2000-11-01

296

Study on natural convection capability of liquid gallium for passive decay heat removal system (PDHRS)  

SciTech Connect

The safety issues of the SFRs are important due to the fact that it uses sodium as a nuclear coolant, reacting vigorously with water and air. For that reason, there are efforts to seek for alternative candidates of liquid metal coolants having excellent heat transfer property and to adopt improved safety features to the SFR concepts. This study considers gallium as alternative liquid metal coolant applicable to safety features in terms of chemical activity issue of the sodium and aims to experimentally investigate the natural convection capability of gallium as a feasibility study for the development of gallium-based passive safety features in SFRs. In this paper, the design and construction of the liquid gallium natural convection loop were carried out. The experimental results of heat transfer coefficient of liquid gallium resulting in heat removal {approx}2.53 kW were compared with existing correlations and they were much lower than the correlations. To comparison of the experimental data with computer code analysis, gallium property code was developed for employing MARS-LMR (Korea version of RELAP) based on liquid gallium as working fluid. (authors)

Kang, S. [Ulsan National Inst. of Science and Technology UNIST, 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulasn Metropolitan City 689-798 (Korea, Republic of); Ha, K. S. [Korea Atomic Energy Research Inst. KAERI, Deokjin-dong, Yuseong-gu, Daejeon, 305-600 (Korea, Republic of); Lee, S. W.; Park, S. D.; Kim, S. M.; Seo, H.; Kim, J. H.; Bang, I. C. [Ulsan National Inst. of Science and Technology UNIST, 100 Banyeon-ri, Eonyang-eup, Ulju-gun, Ulasn Metropolitan City 689-798 (Korea, Republic of)

2012-07-01

297

Technetium-99m DTPA aerosol and gallium scanning in acquired immune deficiency syndrome  

SciTech Connect

In 11 non-smoking AIDS patients suspected of pneumocystis carinii pneumonia (PCP), the results of Tc-99m DTPA aerosol clearances, gallium scans, and arterial blood gases were compared with those of bronchoalveolar lavage (BAL). Nine patients had PCP. All had increased clearances five times higher than the normal (5.6 +/- 2.3% X min-1 vs 1.1 +/- 0.34% X min-1, N = 10, P less than 0.001), suggesting an increased alveolar permeability. Gallium scans were abnormal in six patients but normal or slightly abnormal in the three others. Four of these nine patients had normal chest x-rays. In two of these the gallium scan was abnormal, but in the two others, only the increased Tc-99m DTPA clearances showed evidence of lung disease. Two patients had normal BAL, with normal clearances and gallium scans. Four out of the nine patients with PCP were studied after treatment. Three recovered and had normal clearance and gallium scans. One still had PCP with increased clearance but normal gallium scan. Gallium scanning and Tc-99m DTPA clearance are useful for detecting lung disease in AIDS patients with suspected PCP and for prompting BAL when chest x-rays and PaO/sub 2/ levels are normal. Due to its high sensitivity, a normal Tc-99m DTPA clearance could avoid BAL.

Picard, C.; Meignan, M.; Rosso, J.; Cinotti, L.; Mayaud, C.; Revuz, J.

1987-07-01

298

High-surface Thermally Stable Mesoporous Gallium Phosphates Constituted by Nanoparticles as Primary Building Blocks  

SciTech Connect

In constant, search for micro/mesoporous materials, gallium phosphates, have attracted continued interest due to the large pore size reported for some of these solids in comparison with analogous aluminum phosphates. However up to now, the porosity of gallium phosphates collapsed upon template removal or exposure to the ambient moisture. In the present work, we describe high-surface thermally stable mesoporous gallium phosphates synthesized from gallium propoxide and PCl{sub 3} and different templating agents such as amines (dipropylamine, piperidine and aminopiperidine) and quaternary ammonium salts (C{sub 16}H{sub 33}(CH{sub 3})3NBr and C{sub 16}PyCl). These highly reactive precursors have so far not been used as gallium and phosphate sources for the synthesis of gallophosphates. Conceptually, our present synthetic procedure is based on the fast formation of gallium phosphate nanoparticles via the reaction of gallium propoxide with PCl{sub 3} and subsequent construction of the porous material with nanoparticles as building blocks. The organization of the gallophosphate nanoparticles in stable porous structures is effected by the templates. Different experimental procedures varying the molar composition of the sol-gel, pH and the pretreatment of gallium precursor were assayed, most of them leading to satisfactory materials in terms of thermal stability and porosity. In this way, a series of gallium phosphates with surface are above 200 m{sup 2} g{sup -1}, and narrow pore size from 3 to 6 nm and remarkable thermal stability (up to 550 C) have been prepared. In some cases, the structure tends to show some periodicity and regularity as determined by XRD. The remarkable stability has allowed us to test the catalytic activity of gallophosphates for the aerobic oxidation of alkylaromatics with notable good results. Our report reopens the interest for gallophosphates in heterogeneous catalysis.

V Parvulescu; V Parvulescu; D Ciuparu; C Hardacre; H Garcia

2011-12-31

299

Amorphous Copper Diselenide Thin Films Doped with Gallium and Indium by Laser-Induced Doping  

NASA Astrophysics Data System (ADS)

The laser-induced doping of amorphous copper diselenide (?-CuSe2) thin film with gallium (Ga) and indium (In) was performed to control/improve their electrical and optical properties. The CuSe2 thin films sputtering-deposited using a CuSe2 alloy target were amorphous and remained amorphous after doping with Ga/In. Doping of group-III-elements enhanced the absorption ability of the ?-CuSe2 thin films in the near-infrared spectral regions (800-1500 nm). The insufficient laser-irradiation time to Ga attributed the nonuniform distribution of Ga content around the surface of the ?-CuSe2 thin films, which prevented the incident light from transiting through the thin film, particularly in the visible spectral region (400-800 nm). Consequently, the absorption coefficient increased with the nonuniformly distributed specimen in the visible and near-infrared spectral regions, which improved the mean absorbance of the ?-CuSe2 thin films from 1.03 to 1.66 by decreasing the optical band gap energy from 2.50 eV to 2.10 eV in the same spectral region. The resistivity, carrier concentration and carrier mobility of the ?-CuSe2 thin films were in 3.76×10-4- 3.83×10-3 ? cm, 1.41×1020-2.00×1021cm-3 and 9.9-19.4 cm2/Vs, respectively, regardless of doping, making these films suitable as a wide spectral range absorber layer in photovoltaic applications.

Kim, Nam-Hoon; Jeon, Ji Eun; Cho, Geum-Bae; Lee, Woo-Sun; Choi, Dong-You

2013-04-01

300

Crystallographic alignment of high-density gallium nitride nanowire arrays  

NASA Astrophysics Data System (ADS)

Single-crystalline, one-dimensional semiconductor nanostructures are considered to be one of the critical building blocks for nanoscale optoelectronics. Elucidation of the vapour-liquid-solid growth mechanism has already enabled precise control over nanowire position and size, yet to date, no reports have demonstrated the ability to choose from different crystallographic growth directions of a nanowire array. Control over the nanowire growth direction is extremely desirable, in that anisotropic parameters such as thermal and electrical conductivity, index of refraction, piezoelectric polarization, and bandgap may be used to tune the physical properties of nanowires made from a given material. Here we demonstrate the use of metal-organic chemical vapour deposition (MOCVD) and appropriate substrate selection to control the crystallographic growth directions of high-density arrays of gallium nitride nanowires with distinct geometric and physical properties. Epitaxial growth of wurtzite gallium nitride on (100) ?-LiAlO2 and (111) MgO single-crystal substrates resulted in the selective growth of nanowires in the orthogonal [1 macr1 0] and [001] directions, exhibiting triangular and hexagonal cross-sections and drastically different optical emission. The MOCVD process is entirely compatible with the current GaN thin-film technology, which would lead to easy scale-up and device integration.

Kuykendall, Tevye; Pauzauskie, Peter J.; Zhang, Yanfeng; Goldberger, Joshua; Sirbuly, Donald; Denlinger, Jonathan; Yang, Peidong

2004-08-01

301

Electrical characterisation of magnesium and tellurium implanted indium gallium arsenide  

SciTech Connect

There has been a great deal of interest in the Indium Gallium Arsenide (InGaAs) material system, both lattice matched to Indium Phosphide (InP) as well as material grown pseudomorphically on GaAs because of its importance to optoelectronic devices. In this paper we present some preliminary observations on the electrical properties of In{sub x}Ga{sub 1-x}As on Gallium Arsenide (GaAs) substrate implanted with magnesium with x varying between 0 to 60 atomic %. Our results indicate that p-type activity is difficult to realise in In{sub x}Ga{sub 1-x}As for x > 50%. We also report results of tellurium doubly charged implanted into In{sub 0.53}Ga{sub 0.47}As lattice matched to InP. About 600 angstroms of rf sputtered Aluminum Nitride (AIN) encapsulant was used to carry out 30s isochronal anneals in an optical furnace at temperatures of 600, 700 and 800{degrees}C. Differential Hall effect measurements were performed to provide dopant depth profiles. Good dopant activation and mobilities were obtained.

Gwilliam, R.M.; Sealy, B.J.; Mynard, J.E. [Univ. of Surrey, Guildford (United Kingdom)] [and others

1996-12-31

302

Preparation of negative electron affinity gallium nitride photocathode  

NASA Astrophysics Data System (ADS)

Negative electron affinity (NEA) Gallium Nitride (GaN) photocathode is an ideal new kind of UV photocathode. NEA GaN photocathode is widely used in such fields as high-performance ultraviolet photoelectric detector, electron beam lithography etc. The preparation of negative electron affinity gallium nitride photocathode relates to the growth technology, the cleaning method, the activation method and the evaluation of photocathode. The mainstream growth technology of GaN photocathode such as metal organic chemistry vapor phase deposits technology, molecule beam epitaxial technology and halide vapor phase epitaxial technology were discussed. The chemical cleaning method and the heat cleaning method for GaN photocathode were given in detail. After the chemical cleaning, the atom clean surface was gotten by a 700 °C heat about 20 minutes in the vacuum system. The activation of GaN photocathode can be realized with only Cs or with Cs/O alternately. Using the activation and evaluation system for NEA photocathode, the photocurrent curve during Cs activation process for GaN photocathode was gotten. The evaluation of photocathode can be done by measuring the quantum efficiency. Employing the UV spectral response measurement instrument, the spectral response and quantum efficiency of NEA GaN photocathode were measured. The measured quantum efficiency of reflection-mode NEA GaN photocathode reached up to 37% at 230 nm.

Qiao, Jianliang; Chang, Benkang; Qian, Yunsheng; Du, Xiaoqing; Zhang, Yijun; Wang, Xiaohui

2010-10-01

303

Unilateral gallium-67 uptake in primary tuberculosis of the major salivary glands  

SciTech Connect

Unilateral radionuclide accumulation in salivary glands is an uncommon finding on gallium scintigraphy. The differential diagnosis includes malignant tumors and inflammatory processes of these organs. Two cases of unilateral gallium uptake of the parotid and submandibular gland respectively, verified as solitary tuberculosis, are presented, together with the correlative findings of Tc-99m pertechnetate scintigraphy, sialography, and sonography. None of these imaging modalities is specific enough to provide pathognomonic signs for tuberculosis. When assessing unilateral gallium uptake of the salivary glands, one should be aware of the possibility of tuberculosis.

Bihl, H.; Maier, H.

1987-08-01

304

Identification of a physical metallurgy surrogate for the plutonium—1 wt.?% gallium alloy  

NASA Astrophysics Data System (ADS)

Future plutonium research is expected to be limited due to the downsizing of the nuclear weapons complex and an industry focus on environmental remediation and decommissioning of former manufacturing and research facilities. However, the need to further the understanding of the behavior of plutonium has not diminished. Disposition of high level residues, long-term storage of wastes, and certification of the nuclear stockpile through the Stockpile Stewardship Program are examples of the complex issues that must be addressed. Limited experimental facilities and the increasing cost of conducting plutonium research provide a strong argument for the development of surrogate materials. The purpose of this work was to identify a plutonium surrogate based on fundamental principles such as electronic structure, and then to experimentally demonstrate its viability.

Gibbs, Frank E.; Olson, David L.; Hutchinson, William

2000-07-01

305

Growth and characterization of gallium indium nitrogen arsenide and gallium indium nitrogen phosphide  

NASA Astrophysics Data System (ADS)

Nitrogen incorporation into GaInAs and GaInP based on GaAs (100) substrates has attracted a great deal of attention due to their potential applications in ultra-high-efficiency multijunction solar cells as well as in optoelectronic devices. In order to investigate not yet well-studied material families of III-N-V compounds, we use gas-source molecule beam epitaxy (MBE) method, in which nitrogen radicals are used as the nitrogen precursor, to grow mixed group-V nitride alloy semiconductors with excellent crystallinity. This dissertation is divided into two major parts. In the first part, we use different structures to improve GaInNAs material quality, including strain-compensated GaIn0.08As/GaN0.03As and strained InAs/GaN0.03As0.97 short-period superlattices (SPSLs). The photoluminescence intensity of the SPSLs is 12 times higher than that of random alloys, while electron mobility is improved by a factor of two. InAs/GaN0.03As0.97 SPSL is very promising for 1.3 mum GaInNAs quantum well laser application. Photoconductance measurements show a type-II band lineup for the Ga0.92In0.08As/GaN 0.03As0.97 heterojunction. In the second part, we demonstrate the successful growth of a novel material, GaInNP. Fundamental optical and electrical transport properties of GaInNP are studied. Nitrogen incorporation dramatically reduces the GalnP band gap, which can be successfully explained by the band anticrossing model based on the concept of an anticrossing interaction between localized N states and the extended conduction band states. Rapid thermal annealing improves the optical properties, but decreases the free electron concentration because Si dopant is passivated by N through the formation of Si-N pairs. Band alignment between GaInNP and GaAs is also investigated. GaInNP is an ideal material for tunnel-collector heterojunction bipolar transistors (HBTs). In comparing the properties of GaInNP and GaInNAs, great similarities are found in terms of the effect of nitrogen incorporation. Here, the band anticrossing model successfully explains the band gap reduction and predicts an increase of the electron effective mass for both material.

Hong, Yuguang

306

Efficient bifunctional gallium-68 chelators for positron emission tomography: tris(hydroxypyridinone) ligands  

PubMed Central

A new tripodal tris(hydroxypyridinone) bifunctional chelator for gallium allows easy production of 68Ga-labelled proteins rapidly under mild conditions in high yields at exceptionally high specific activity and low concentration. PMID:21623436

Berry, David J.; Ma, Yongmin; Ballinger, James R.; Tavare, Richard; Koers, Alexander; Sunassee, Kavitha; Zhou, Tao; Nawaz, Saima; Mullen, Gregory E. D.; Hider, Robert C.; Blower, Philip J.

2014-01-01

307

Empyema of the gallbladder detected by gallium scan and abdominal ultrasonography  

SciTech Connect

A case history of patient with a abnormal gallium uptake and sonogram in the region of the gallbladder is described. The abnormality was interpreted as empyema of the gallbladder and later proven surgically. A liver-spleen scan was normal except for slight prominence of the hilar structures. Gallium citrate Ga-67 scans done at 24 and 48 hours showed a persistent area of increased tracer localization around the gallbladder with a central clear zone in the latter scan. Ultrasonography revealed poor definition and slight thickening of the gallbladder wall. Because of the lack of specificity of gallium scans, the combination of ultrasonic imaging and gallium uptake scans appears much superior in diagnostic efficiency than either of the two alone. The sequence of performing these two examinations does not seem to be critical though it was prefered that the scintigraphy precede the sonography.

Garcia, O.M.; Kovac, A.; Plauche, W.E.

1981-08-01

308

Gallium-67 detection of intramammary injection sites secondary to intravenous drug abuse  

SciTech Connect

A case of gallium localization within the breast occurred secondary to intravenous drug abuse. In the appropriate clinical setting, prior self-administered injections should be considered as a cause of Ga-67 accumulation at unusual sites.

Swayne, L.C. (Morristown Memorial Hospital, NJ (USA))

1989-09-01

309

Ultrasonic cavitation of molten gallium: formation of micro- and nano-spheres.  

PubMed

Pure gallium has a low melting point (29.8°C) and can be melted in warm water or organic liquids, thus forming two immiscible liquid phases. Irradiation of this system with ultrasonic energy causes cavitation and dispersion of the molten gallium as microscopic spheres. The resultant spheres were found to have radii range of 0.2-5 ?m and they do not coalesce upon cessation of irradiation, although the ambient temperature is well above the m.p. of gallium. It was found that the spheres formed in water are covered with crystallites of GaO(OH), whereas those formed in organic liquids (hexane and n-dodecane) are smooth, lacking such crystallites. However, Raman spectroscopy revealed that the spheres formed in organic liquids are coated with a carbon film. The latter may be the factor preventing their coalescence at temperatures above the m.p. of gallium. PMID:24296070

Kumar, Vijay Bhooshan; Gedanken, Aharon; Kimmel, Giora; Porat, Ze'ev

2014-05-01

310

Gallium-67 scintigraphy, bronchoalveolar lavage, and pathologic changes in patients with pulmonary sarcoidosis  

SciTech Connect

The intensity of gallium-67 scintiscans, lymphocyte counts in bronchoalveolar lavage fluid, and pathologic changes were studied in 26 patients with untreated pulmonary sarcoidosis. Noncaseating granulomas were recognized with significantly greater frequency in stage 2 (80 percent; 8/10 cases) than in stage 1 (43 percent; 6/14 cases). Alveolitis showed little relation to the roentgenographic stage. There was a strong correlation between the intensity of gallium uptake in pulmonary parenchyma and the detection rate of granuloma; however, the detection rate of alveolitis was not statistically different from the intensity of gallium uptake. A highly significant correlation was revealed between the lymphocyte counts in bronchoalveolar lavage fluid and the intensity of alveolitis. These observations suggest that the gallium uptake reflects mainly the presence of granuloma, and the lymphocyte count in bronchoalveolar lavage fluid reflects the intensity of alveolitis in patients with pulmonary sarcoidosis.

Abe, S.; Munakata, M.; Nishimura, M.; Tsuneta, Y.; Terai, T.; Nakano, I.; Ohsaki, Y.; Kawakami, Y.

1984-05-01

311

All-optical Wavelength Conversion in Aluminum Gallium Arsenide at Telecommunications Wavelengths.  

E-print Network

??This thesis aims at both developing highly nonlinear Aluminum Gallium Arsenide waveguides(AlGaAs) and demonstrating all-optical wavelength conversion via cross-phase modulation in AlGaAs waveguides at telecommunications… (more)

Ng, Wing-Chau

2011-01-01

312

Preliminary survey report: control technology for gallium arsenide processing at Hewlett Packard, San Jose, California  

SciTech Connect

A walk-through survey of the Hewlett Packard Company facility in San Jose, California, was prompted by an interest in the use of gallium arsenide as an alternative to silicon for the semiconductor industry. This facility produced gallium-arsenide and gallium phosphide Potential hazards existed from solvents, acids, and gases employed in wafer production. Some of the solvents included fluorocarbon compounds, xylene, and 1,1,1-trichloroethane Arsine, phosphine, hydrogen, and silane gases were used in the production processes. Worker exposures to gallium arsenide or arsenic dust were lower during the cleaning operation than they had been in other similar facilities, perhaps due to the small size of the crystal pullers used at this particular facility. According to the author, this facility is a possible candidate for an in-depth industry survey, but may not be representative of the entire industry.

Lenihan, K.L.

1987-04-01

313

The dynamically light-induced low-reflectivity state in gallium  

Microsoft Academic Search

Summary form only given. Confined elemental gallium has recently attracted much attention because of its unique nonlinear optical properties on the verge of a structural phase transition. We report, for the first time, a light-induced state of the gallium-silica interface with specular reflectivity as low as 6%. The low-reflectivity state can be induced at light power levels starting around one

R. T. Bratfalean; S. Dhanjal; N. Zheludev; P. Petropoulos; D. J. Richardson; V. I. Emelyanov

2000-01-01

314

The determination of titanium, germanium and gallium by charged particle activation analysis  

E-print Network

THE DETFRMINATION OF TITANIUiil, GEKIA?UM AND GALLIUM 'BY CHARGED PARTICLE ACTIVATION ANALYSIS A Thesis LEO ROBERT NOVA@ Submitted to the Graduate College of Tezas MI University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE May 1975 Major Subject: Chemistry THE DETERMINATION OF TITANIUM GERMANIUM AND GALLIUM BY CHARGED PARTICLE ACTIVATION ANALYSIS A Thesis by LEO ROBERT NOVAK Approved as to style and content by: (Chairman of Committee) Emile A...

Novak, Leo Robert

2012-06-07

315

Are oral cathartics of value in optimizing the gallium scan. Concise communication  

SciTech Connect

The normal intestinal secretion of 9-15% of an administered dose of gallium-67 may prevent early detection of intra-abdominal disease. We randomized 50 patients to receive either no bowel preparation or 30 cc of milk of magnesia plus 5 cc of cascara. No significant difference was found between the two groups in frequency with which gallium interfered with readings or time to complete the study.

Silberstein, E.B.; Fernandez-Ulloa, M.; Hall, J.

1981-05-01

316

Polarity control in gallium nitride epilayers grown by Metalorganic Chemical Vapor Deposition  

Microsoft Academic Search

Polarity control of gallium nitride (GaN) on c-plane sapphire substrate was studied via low pressure Metalorganic Chemical Vapor Deposition (MOCVD). Under mass-transport-limited growth regime with a given process supersaturation, the polarities of GaN thin films (i.e. gallium (Ga) and nitrogen (N)-polarities) depended on specific treatments of the sapphire substrate prior to GaN deposition, in addition, identical growth rates for both

Seiji Mita

2007-01-01

317

Tumoral calcinosis associated with sarcoidosis and positive bone and gallium imaging  

SciTech Connect

A 63-year-old female with biopsy proven tumoral calcinosis presented with progressive and recurrent swelling and tenderness of the right hip, thigh, elbow, and wrist. Both gallium and bone imaging demonstrated intense, congruent uptake in these areas. This is the third case of tumoral calcinosis with sarcoidosis documented in the literature. However, these are the first published bone and gallium scans in a patient with a history of sarcoidosis and tumoral calcinosis.

Wolpe, F.M.; Khedkar, N.Y.; Gordon, D.; Werner, P.; Shirazi, P.; Al-Sabban, M.H.

1987-07-01

318

Heterotopic ossification (myositis ossificans) in acquired immune deficiency syndrome. Detection by gallium scintigraphy  

SciTech Connect

A case of heterotopic ossification (myositis ossificans) secondary to the central nervous system complications of acquired immune deficiency syndrome (AIDS) is reported. Because of the overwhelming suspicion of infection in this patient, this diagnosis was not considered until a gallium scan revealed the typical findings of heterotopic ossification. Because of the increasing utilization of gallium imaging in the AIDS population, every imaging specialist should be aware of this potential disorder.

Drane, W.E.; Tipler, B.M.

1987-06-01

319

Fabrication of an optically driven 10 GHz ring resonator on a gallium arsenide substrate  

E-print Network

FABRICATION OF AN OPTICALLY DRIVEN 10 GHZ RING RESONATOR ON A GALLIUM ARSENIDE SUBSTRATE A Thesis by DOUGLAS SCOTT MCGREGOR Submitted to the Office of Graduate Studies of Texas A@M University in partia1 fulfillment of the requirements... for the degree of MASTER OF SCIENCE August ]9gg Major Subject: Electrical Engineering FABRICATION OF AN OPTICALLY DRIVEN 10 GHZ RING RESONATOR ON A GALLIUM ARSENIDE SUBSTRATE A Thesis DOUGLAS SCOTT MCGREGOR Approved as to style and content by: Mark H...

McGregor, Douglas Scott

2012-06-07

320

Gallium compounds in solar cells. (Latest citations from the Aerospace database). Published Search  

SciTech Connect

The bibliography contains citations concerning the use of gallium compounds in solar cells to increase solar cell efficiency. Computer models, theories, and performance tests are included. Gallium compounds used in thin film cells, cascade solar cells, large area solar cells, cells designed for industrial and space applications, and as antireflection coatings are discussed. Resistance to radiation damage, cooling to improve efficiency, grain boundary behavior, and economic considerations are also covered. (Contains 250 citations and includes a subject term index and title list.)

Not Available

1993-12-01

321

Bit-systolic arithmetic arrays using dynamic differential gallium arsenide circuits  

NASA Technical Reports Server (NTRS)

A new family of gallium arsenide circuits for fine grained bit-systolic arithmetic arrays is introduced. This scheme combines features of two recent techniques of dynamic gallium arsenide FET logic and differential dynamic single-clock CMOS logic. The resulting circuits are fast and compact, with tightly constrained series FET propagation paths, low fanout, no dc power dissipation, and depletion FET implementation without level shifting diodes.

Beagles, Grant; Winters, Kel; Eldin, A. G.

1992-01-01

322

Thin-film gallium arsenide homojunction solar cells on recrystallized germanium and large-grain germanium substrates  

SciTech Connect

Polycrystalline gallium arsenide films of 10-..mu..m thickness deposited on tungsten/graphite substrates by the reaction between gallium, hydrogen chloride, and arsine have been used for the fabrication of thin-film homojunction solar cells. The major problem associated with polycrystalline gallium arsenide thin-film cells is the grain-boundary shunting effect. In order to prepare solar cells with conversion efficiency higher than 10%, gallium arsenide films with large grains are necessary. Unlike gallium arsenide, germanium films can be easily recrystallized to enhance the grain size. Thin-film gallium arsenide solar cells of the p/sup +//n configuration with an AM1 efficiency of about 10% have been prepared using recrystallized germanium and large-grain germanium substrates.

Chu, S.S.; Chu, T.L.; Han, Y.X.

1986-07-15

323

Results from the Soviet-American gallium experiment  

SciTech Connect

A radiochemical {sup 71}Ga-{sup 71}Ge experiment to determine the primary flux of neutrinos from the Sun has begun operation at the Baksan Neutrino Observatory. The number of {sup 71}Ge atoms extracted from thirty tons of gallium was measured in five runs during the period of January to July 1990. Assuming that the extraction efficiency for {sup 71}Ge atoms produced by solar neutrinos is the same as from natural Ge carrier, we observed the capture rate to be 20 + 15/{minus}20 (stat) {plus minus} 32 (syst) SNU, resulting in a limit of less than 79 SNU (90% CL). This is to be compared with 132 SNU predicted by the Standard Solar Model.

Abazov, A.I.; Anosov, O.L.; Faizov, E.L.; Gavrin, V.N.; Kalikhov, A.V.; Knodel, T.V.; Knyshenko, I.I.; Kornoukhov, V.N.; Mezentseva, S.A.; Mirmov, I.N.; Ostrinsky, A.V.; Pshukov, A.M.; Revzin, N.E.; Shikhin, A.A.; Timofeyev, P.V.; Veretenkin, E.P.; Vermul, V.M.; Zatsepin, G.T. (AN SSSR, Moscow (USSR). Inst. Yadernykh Issledovanij); Bowles, T.J.; Cleveland, B.T.; Elliott, S.R.; O'Brien, H.A.; Wark, D.L.; Wilkerson, J.F.

1991-01-01

324

Results from the Soviet-American gallium experiment  

SciTech Connect

A radiochemical {sup 71}Ga-{sup 71}Ge experiment to determine the primary flux of neutrinos from the Sun has begun operation at the Baksan Neutrino Observatory. The number of {sup 71}Ge atoms extracted from thirty tons of gallium was measured in five runs during the period of January to July 1990. Assuming that the extraction efficiency for {sup 71}Ge atoms produced by solar neutrinos is the same as from natural Ge carrier, we observed the capture rate to be 20 + 15/{minus}20 (stat) {plus_minus} 32 (syst) SNU, resulting in a limit of less than 79 SNU (90% CL). This is to be compared with 132 SNU predicted by the Standard Solar Model.

Abazov, A.I.; Anosov, O.L.; Faizov, E.L.; Gavrin, V.N.; Kalikhov, A.V.; Knodel, T.V.; Knyshenko, I.I.; Kornoukhov, V.N.; Mezentseva, S.A.; Mirmov, I.N.; Ostrinsky, A.V.; Pshukov, A.M.; Revzin, N.E.; Shikhin, A.A.; Timofeyev, P.V.; Veretenkin, E.P.; Vermul, V.M.; Zatsepin, G.T. [AN SSSR, Moscow (USSR). Inst. Yadernykh Issledovanij; Bowles, T.J.; Cleveland, B.T.; Elliott, S.R.; O`Brien, H.A.; Wark, D.L.; Wilkerson, J.F. [Los Alamos National Lab., NM (United States); Davis, R. Jr.; Lande, K. [Pennsylvania Univ., Philadelphia, PA (United States); Cherry, M.L. [Louisiana State Univ., Baton Rouge, LA (United States); Kouzes, R.T. [Princeton Univ., NJ (United States)

1991-12-31

325

Compilation of gallium resource data for bauxite deposits  

USGS Publications Warehouse

Gallium (Ga) concentrations for bauxite deposits worldwide have been compiled from the literature to provide a basis for research regarding the occurrence and distribution of Ga worldwide, as well as between types of bauxite deposits. In addition, this report is an attempt to bring together reported Ga concentration data into one database to supplement ongoing U.S. Geological Survey studies of critical mineral resources. The compilation of Ga data consists of location, deposit size, bauxite type and host rock, development status, major oxide data, trace element (Ga) data and analytical method(s) used to derive the data, and tonnage values for deposits within bauxite provinces and districts worldwide. The range in Ga concentrations for bauxite deposits worldwide is

Schulte, Ruth F.; Foley, Nora K.

2014-01-01

326

Gallium-67 lung uptake: conjugate-view technique  

SciTech Connect

A conjugate-view technique is derived for calculation of absolute gallium-67 (Ga-67) uptake from scintillation-camera images. The technique combines counts of posterior and anterior images of the lung with an attenuation correction obtained from cobalt-57 (Co-57) transmission imaging. The formulation is such that the effects of Compton scatter build-up are accounted for. Studies utilizing a canine model indicated that, normally, more activity is located in the chest wall than in the lungs. Calculations were performed using a three-component model comparing results obtained with the conjugate-view approach to the actual uptake. These calculations suggest that an assumption of uniform activity distribution allows an accuracy of approximately +/- 10% over a broad range of body-part thicknesses and uptake by the lungs. It was concluded that the conjugate-view technique is necessarily approximate but can provide clinically useful results.

Grossman, L.W.; Fernandez-Ulloa, M.; Lukes, S.J.; Mantil, J.

1985-12-01

327

A high open-circuit voltage gallium nitride betavoltaic microbattery  

NASA Astrophysics Data System (ADS)

A high open-circuit voltage betavoltaic microbattery based on a gallium nitride (GaN) p-i-n homojunction is demonstrated. As a beta-absorbing layer, the low electron concentration of the n-type GaN layer is achieved by the process of Fe compensation doping. Under the irradiation of a planar solid 63Ni source with activity of 0.5 mCi, the open-circuit voltage of the fabricated microbattery with 2 × 2 mm2 area reaches as much as 1.64 V, which is the record value reported for betavoltaic batteries with 63Ni source, the short-circuit current was measured as 568 pA and the conversion effective of 0.98% was obtained. The experimental results suggest that GaN is a high-potential candidate for developing the betavoltaic microbattery.

Cheng, Zaijun; Chen, Xuyuan; San, Haisheng; Feng, Zhihong; Liu, Bo

2012-07-01

328

Coated gallium arsenide neutron detectors : results of characterizationmeasurements.  

SciTech Connect

Effective detection of special nuclear materials (SNM) is essential for reducing the threat associated with stolen or improvised nuclear devices. Passive radiation detection technologies are primarily based on gamma-ray detection and subsequent isotope identification or neutron detection (specific to neutron sources and SNM). One major effort supported by the Department of Homeland Security in the area of advanced passive detection is handheld or portable neutron detectors for search and localization tasks in emergency response and interdiction settings. A successful SNM search detector will not only be able to confirm the presence of fissionable materials but also establish the location of the source in as short of time as possible while trying to minimize false alarms due to varying background or naturally occurring radioactive materials (NORM). For instruments based on neutron detectors, this translates to detecting neutrons from spontaneous fission or alpha-n reactions and being able to determine the direction of the source (or localizing the source through subsequent measurements). Polyethylene-coated gallium arsenide detectors were studied because the detection scheme is based on measuring the signal in the gallium arsenide wafers from the electrical charge of the recoil protons produced from the scattering of neutrons from the hydrogen nucleus. The inherent reaction has a directional dependence because the neutron and hydrogen nucleus have equivalent masses. The assessment and measurement of polyethylene-coated gallium arsenide detector properties and characteristics was the first phase of a project being performed for the Department of Homeland Security and the results of these tests are reported in this report. The ultimate goal of the project was to develop a man-portable neutron detection system that has the ability to determine the direction of the source from the detector. The efficiency of GaAs detectors for different sizes of polyethylene layers and different angles between the detector and the neutron source were determined. Preliminary measurements with a neutron generator based on a deuterium-tritium reaction ({approx}14 MeV neutrons) were performed and the results are discussed. This report presents the results of these measurements in terms of efficiency and angular efficiency and compares them to Monte Carlo calculations to validate the calculation scheme in view of further applications. Based on the results of this study, the polyethylene-coated gallium arsenide detectors provide adequate angular resolution based on proton recoil detection from the neutron scattering reaction from hydrogen. However, the intrinsic efficiency for an individual detector is extremely low. Because of this low efficiency, large surface area detectors ( or a large total surface area from many small detectors) would be required to generate adequate statistics to perform directional detection in near-real time. Large surface areas could be created by stacking the detector wafers with only a negligible attenuation of source neutrons. However, the cost of creating such a large array of GaAs is cost-prohibitive at this time.

Klann, R. T.; Perret, G.; Sanders, J.

2006-09-29

329

Design and Performance Estimates of an Ablative Gallium Electromagnetic Thruster  

NASA Technical Reports Server (NTRS)

The present study details the high-power condensable propellant research being conducted at NASA Glenn Research Center. The gallium electromagnetic thruster is an ablative coaxial accelerator designed to operate at arc discharge currents in the range of 10-25 kA. The thruster is driven by a four-parallel line pulse forming network capable of producing a 250 microsec pulse with a 60 kA amplitude. A torsional-type thrust stand is used to measure the impulse of a coaxial GEM thruster. Tests are conducted in a vacuum chamber 1.5 m in diameter and 4.5 m long with a background pressure of 2 microtorr. Electromagnetic scaling calculations predict a thruster efficiency of 50% at a specific impulse of 2800 seconds.

Thomas, Robert E.

2012-01-01

330

Sol-gel synthesis and characterization of yttrium gallium garnets  

NASA Astrophysics Data System (ADS)

Precursor powders for yttrium gallium garnet (Y3Ga5O12, YGG) were prepared by a simple sol-gel method based on the formation of metal chelates in aqueous solvents. A systematic study of sol-gel technique synthesized YGG samples is presented using different complexing agents. Six high-purity organic substances were used as complexing agents, namely, tartaric acid, 1,2-ethanediol, citric acid, ethylene diamine tetra-acetic acid (EDTA), malonic acid, and oxalic acid. These agents were found to influence the characteristics of the end products, in particular their homogeneity. The phase purity, composition, and microstructure of the polycrystalline samples were studied by thermoanalytical methods (TGADTA), x-ray diffraction (XRD) analysis, IR spectroscopy, and scanning electron microscopy (SEM). From the typical XRD patterns of different synthesis products it is concluded that only the use tartaric acid, 1,2-ethanediol, citric acid, and EDTA yields a single YGG phase.

Leleckaite, Asta; Urbonaite, Sigita; Tõnsuaadu, Kaia; Kareiva, Aivaras

2005-08-01

331

An interrogation of the zinc oxide gallium oxide phase space by plasma enhanced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Polycrystalline metal oxide thin films were deposited by mixing combinations of diethylzinc and trimethylgallium into an oxygen plasma. Plasma-enhanced chemical vapor deposition was shown to be a flexible tool for materials exploration, as the entire zinc-gallium-oxide phase space was explored by simply altering precursor flow rates. Film identification was performed using measurements of intrinsic optical properties as well as X-ray diffraction. The compounds synthesized included zinc oxide, gallium-doped zinc oxide (ZnO:Ga), the spinel ZnGa2O4, and amorphous gallium oxide. A phase diagram was established for PECVD synthesis as a function of the organometallic precursor composition. It was found that gallium addition had a profound impact on both the deposition rate and resistivity of the films. Small levels the gallium addition produced an order of magnitude improvement in both deposition rate and electrical properties. When the gallium fraction was >50% the deposition rate saturated and the films were insulating. Optical emission spectroscopy was used to probe the plasma chemistry of the system. It was shown to be quite complex, typified by the example that decreasing the diethylzinc fraction in the feedstream dramatically increased the density of atomic zinc in the plasma.

Robbins, J. J.; Fry, C.; Wolden, C. A.

2004-03-01

332

High-Temperature Decomposition of Brønsted Acid Sites in Gallium-Substituted Zeolites  

SciTech Connect

The dehydroxylation of Broensted acid sites (BAS) in Ga-substituted zeolites was investigated at temperatures up to 850 C using X-ray absorption spectroscopy (XAS), Fourier transform infrared spectroscopy (FTIR), and mass spectrometry-temperature programmed desorption (MS-TPD). X-ray absorption near-edge spectroscopy (XANES) revealed that the majority of gallium has tetrahedral coordination even after complete dehydroxylation. The interatomic gallium-oxygen distance and gallium coordination number determined by extended X-ray absorption fine structure (EXAFS) are consistent with gallium in tetrahedral coordination at low T (< 550 C). Upon heating Ga-Beta and Ga-ZSM5 to 850 C, analysis of the EXAFS showed that 70 and 80% of the gallium was still in tetrahedral coordination. The remainder of the gallium was found to be in octahedral coordination. No trigonal Ga atoms were observed. FTIR measurements carried out at similar temperatures show that the intensity of the OH vibration due to BAS has been eliminated. MS-TPD revealed that hydrogen in addition to water evolved from the samples during dehydroxylation. This shows that dehydrogenation in addition to dehydration is a mechanism that contributes to BAS decomposition. Dehydrogenation was further confirmed by exposing the sample to hydrogen to regenerate some of the BAS as monitored by FTIR and MS-TPD.

K Al-majnouni; N Hould; W Lonergan; D Vlachos; R Lobo

2011-12-31

333

Study of liquid gallium at high pressure using synchrotron x-ray  

SciTech Connect

Liquid gallium has been studied at high pressure up to 2 GPa and ambient temperature in a diamond anvil cell using high energy synchrotron x-ray beam. The total x-ray scattering data of liquid gallium were collected up to Q = 12 A{sup -1} and analyzed using pair distribution functions (PDF). The results indicate that the first nearest neighbor peak and second nearest neighbor (shoulder) peak of PDF in liquid gallium does not change with pressure, whereas the higher order (i.e., third and fourth) nearest neighbor peaks shift towards shorter distance with increasing pressure. Reverse Monte Carlo modeling based on the observed data shows that the coordination number in the liquid gallium increases with pressure from 10.5 at 0.3 GPa to 11.6 at 2 GPa. An atomic arrangement similar to the crystalline phase of Ga(II) with coordination number of 12 is proposed for the locally dense-packed rigid unit in liquid gallium. The volume compression data derived from the structure modeling yield a bulk modulus of 12.1(6) GPa for liquid gallium.

Yu, Tony; Guo Quanzhong; Parise, John [Department of Geosciences, Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794-2100 (United States); Chen Jiuhua [Department of Geosciences, Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794-2100 (United States); Department of Mechanical and Materials Engineering, Center for the Study of Matters at Extreme Conditions, Florida International University, Miami, Florida 33199 (United States); Ehm, Lars [Department of Geosciences, Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794-2100 (United States); National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States); Huang Shu [Department of Mechanical and Materials Engineering, Center for the Study of Matters at Extreme Conditions, Florida International University, Miami, Florida 33199 (United States); Luo Shengnian [Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2012-06-01

334

Immunosuppressive therapy in patients with congestive cardiomyopathy and myocardial uptake of gallium-67  

SciTech Connect

Thirty-nine patients with idiopathic congestive cardiomyopathy underwent gallium-67 scintigraphy. Twenty had no evidence of myocardial uptake (group I) and 19 had demonstrable myocardial gallium-67 activity (group II). There was no significant difference in age, sex, duration of symptoms, antecedent viral illness, left ventricular end-diastolic pressure, pulmonary artery systolic pressure, or ejection fraction between the two groups. Fifteen patients in group II were treated with prednisone and azathioprine for a minimum of 8 months. Nine of 15 patients were clinically unchanged and gallium-67 scans remained positive (group IIa). Six patients had significant improvement and resolution of myocardial gallium-67 uptake (group IIb). The mean change in ejection fraction was +0.2% in group I, -4.8% in Group IIa, and +13.8% in group IIb. There were five deaths in group I (25% mortality), three in group IIa (33% mortality), and no deaths in group IIb. The only significant difference between patients in group IIa and those in group IIb was a greater left ventricular posterior wall thickness in group IIa patients. Twenty control patients without cardiac disease had negative gallium-67 scans. We conclude that gallium-67 myocardial scintigraphy may be a useful test for predicting the response to prednisone and azathioprine therapy.

O'Connell, J.B.; Robinson, J.A.; Henkin, R.E.; Gunnar, R.M.

1981-10-01

335

Immunosuppressive therapy in patients with congestive cardiomyopathy and myocardial uptake of Gallium-67  

SciTech Connect

Thirty-nine patients with idiopathic congestive cardiomyopathy underwent gallium-67 scintigraphy. Twenty had no evidence of myocardial uptake (group I) and 19 had demonstrable myocardial gallium-67 activity (group II). There was no significant difference in age, sex, duration of symptoms, antecedent viral illness, left ventricular end-diastolic pressure, pulmonary artery systolic pressure, or ejection fraction between the two groups. Fifteen patients in group II were treated with prednisone and azathioprine for a minimum of 8 months. Nine of 15 patients were clinically unchanged and gallium-67 scans remained positive (group IIa). Six patients had significant improvement and resolution of myocardial gallium-67 uptake (group IIb). The mean change in ejection fraction was +0.2% in group I, -4.8% in Group IIa, and +13.8% in group IIb. There were five deaths in group I (25% mortality), three in group IIa (33% mortality), and no deaths in group IIb. The only significant difference between patients in group IIa and those in group IIb was a greater left ventricular posterior wall thickness in group IIa patients. Twenty control patients without cardiac disease had negative gallium-67 scans. We conclude that gallium-67 myocardial scintigraphy may be a useful test for predicting the response to prednisone and azathioprine therapy.

O'Connell, J.B.; Robinson, J.A.; Henkin, R.E.; Gunnar, R.M.

1981-10-01

336

Gallium-68: a systematic review of its nononcological applications.  

PubMed

The increased availability of PET facilities worldwide has sparked renewed interest in the use of generator-produced tracers such as gallium-68 (Ga). Imaging with Ga provides exciting opportunities in terms of new ligand-labelling possibilities and the exploration of novel clinical applications. The aim of the study was to summarize and appraise what has been published on the clinical applications of Ga outside oncology practice. This systematic review was based on the PRISMA guidelines. Databases searched include PubMed, Medline, Scopus, Web of Science and Google Scholar. The following search strategy was used: 'Ga' OR 'Gallium' (all fields) NOT the following (title and abstract): Oncology/NET/neuroendocrine tumour/tumor/DOTATOC, DOTATATE, DOTANOC. These results were further limited to English publications, which resulted in 205 publications on PubMed. After duplicates and irrelevant articles were removed, 72 publications remained for inclusion. Only those studies in which compounds were labelled with Ga for applications other than in oncology-related indications were included. Publications in which the focus was on oncology-related applications of Ga imaging or in which the emphasis was on aspects relating to generators, radiochemistry or physics were excluded. Although a multitude of tracers have been labelled with Ga over several decades, it has not been established in routine clinical practice yet. In addition, neuroendocrine and other oncological applications have dominated the field until relatively recently following reports of applications in infection and inflammation. The majority of publications to date involve small numbers of subjects in mainly preclinical settings. Differences in methodology preclude grouping of studies to reach a clear conclusion. There is wide scope for Ga tracer application outside oncological practice, which remains greatly underutilized. Larger clinical trials are needed to validate these applications. PMID:23812409

Vorster, Mariza; Maes, Alex; Van deWiele, Christophe; Sathekge, Mike

2013-09-01

337

Study of Magnetohydrodynamic Surface Waves on Liquid Gallium  

SciTech Connect

Magnetohydrodynamic (MHD) surface waves on liquid gallium are studied theoretically and experimentally in the small magnetic Reynolds number limit. A linear dispersion relation is derived when a horizontal magnetic field and a horizontal electric current is imposed. No wave damping is found in the shallow liquid limit while waves always damp in the deep liquid limit with a magnetic field parallel to the propagation direction. When the magnetic field is weak, waves are weakly damped and the real part of the dispersion is unaffected, while in the opposite limit waves are strongly damped with shortened wavelengths. In a table-top experiment, planar MHD surface waves on liquid gallium are studied in detail in the regime of weak magnetic field and deep liquid. A non-invasive diagnostic accurately measures surface waves at multiple locations by reflecting an array of lasers off the surface onto a screen, which is recorded by an Intensified-CCD camera. The measured dispersion relation is consistent with the linear theory with a reduced surface tension likely due to surface oxidation. In excellent agreement with linear theory, it is observed that surface waves are damped only when a horizontal magnetic field is imposed parallel to the propagation direction. No damping is observed under a perpendicular magnetic field. The existence of strong wave damping even without magnetic field suggests the importance of the surface oxide layer. Implications to the liquid metal wall concept in fusion reactors, especially on the wave damping and a Rayleigh-Taylor instability when the Lorentz force is used to support liquid metal layer against gravity, are discussed.

Hantao Ji; William Fox; David Pace; H.L. Rappaport

2004-05-13

338

Amorphous metal alloys produced by mechanical alloying  

SciTech Connect

Mechanical alloying is a powder metallurgy method used in commercial production of high temperature superalloys. Under specific conditions, mechanical alloying allows the synthesis of amorphous metal alloys from mixtures of pure metal powders or from the powders of intermetallic compounds. Because the amorphizing transformation during mechanical alloying is a solid state reaction, most of the difficulties related to the amorphization by rapid solidification of melts can be avoided. Mechanical alloying allows the synthesis of amorphous alloys from metals with high melting temperatures and the resulting alloys have interesting properties such as high hardness and high crystallization temperatures. We used mechanical alloying for the synthesis of amorphous alloys in the binary alloy systems Nl-Sn, Nb-Si and Al-Hf. The amorphous alloy powders were characterized by x-ray diffraction, differential scanning calorimetry, scanning and transmission electron microscopy and hardness measurements. Produced alloys were compacted by hot pressing and the obtained compacts were characterized by x-ray diffraction, density and hardness measurements and by optical and scanning electron microscopy. The results of the amorphization and compaction studies are presented and discussed together with the characteristics of the mechanical alloying process. 15 refs., 5 figs.

Tiainen, T.J.; Schwarz, R.B.

1989-01-01

339

Request for assistance in reducing the potential risk of developing cancer from exposure to gallium arsenide in the microelectronics industry  

SciTech Connect

Various methods through which exposure to gallium-arsenide might be reduced in the microelectronics industry were discussed. While there were no reported studies showing ill effects in workers from exposure to gallium arsenide or gallium particulates, three studies in animals indicated that gallium arsenide dissociates into gallium and arsenic in biological tissue, the latter being a carcinogen. NIOSH Recommended Exposure Limit (REL) for arsenic was 2 micrograms/cubic meter air (microg/cu m). NIOSH recommends control of worker exposure to gallium arsenide by observing NIOSH REL for inorganic arsenic, and that concentration of gallium arsenide in air be estimated by determining arsenic. Workers should be educated in possible hazards connected with gallium arsenide exposure. Proper engineering controls should be installed during production of microelectronic devices where exposure to gallium-arsenide is likely. Personal protective clothing and equipment should be available to workers, and proper procedures for washing, removal of wastes, transport, and disposal of contaminated materials should be explained and carried out. Specific safety recommendations are offered for use during crystal growth, crystal puller cleaning, crystal surface grinding and sawing, and wafer polishing, backlapping, and dicing.

Not Available

1987-10-01

340

Saddle-like deformation in a dielectric elastomer actuator embedded with liquid-phase gallium-indium electrodes  

NASA Astrophysics Data System (ADS)

We introduce a dielectric elastomer actuator (DEA) composed of liquid-phase Gallium-Indium (GaIn) alloy electrodes embedded between layers of poly(dimethylsiloxane) (PDMS) and examine its mechanics using a specialized elastic shell theory. Residual stresses in the dielectric and sealing layers of PDMS cause the DEA to deform into a saddle-like geometry (Gaussian curvature K <0). Applying voltage ? to the liquid metal electrodes induces electrostatic pressure (Maxwell stress) on the dielectric and relieves some of the residual stress. This reduces the longitudinal bending curvature and corresponding angle of deflection ?. Treating the elastomer as an incompressible, isotropic, NeoHookean solid, we develop a theory based on the principle of minimum potential energy to predict the principal curvatures as a function of ?. Based on this theory, we predict a dependency of ? on ? that is in strong agreement with experimental measurements performed on a GaIn-PDMS composite. By accurately modeling electromechanical coupling in a soft-matter DEA, this theory can inform improvements in design and fabrication.

Wissman, J.; Finkenauer, L.; Deseri, L.; Majidi, C.

2014-10-01

341

Structure and phase stability of a Pu-0.42 wt.% Ga alloy  

NASA Astrophysics Data System (ADS)

This paper describes the characterisation of a cast plutonium-gallium (Pu-0.42 wt.% Ga) alloy, both in the as-cast condition as well as following an homogenising heat treatment. The alloy was subjected to density measurements, differential scanning calorimetry (DSC), dilatometry, optical microscopy, electron probe micro-analysis (EPMA), X-ray diffraction (XRD) and hardness measurements. The Ga content is insufficient to retain a wholly delta-Pu (?-Pu) phase in the as-cast condition. However, the 250-h heat treatment at 450 °C is sufficient to redistribute the Ga resulting in an apparently stable ?-Pu phase. DSC and dilatometry did not indicate the presence of any alpha-Pu (?-Pu) phase in the heat-treated alloy. XRD patterns of the alloys also showed ?-Pu to be present, although in the case of the heat-treated alloy this may be a consequence of incomplete removal of the transformed surface layer during the electro-polishing process. The stability of the ?-Pu phase in the heat-treated alloy was evaluated by cooling specimens to sub-zero temperatures. The alloy exhibited a high degree of stability when subjected to cold treatments at temperatures of between -50 °C and -90 °C.

Wheeler, D. W.; Ennaceur, S. M.; Matthews, M. B.; Roussel, P.

2014-09-01

342

LO-plasmon modes in doped gallium arsenide/aluminum gallium arsenide superlattices  

NASA Astrophysics Data System (ADS)

A great deal of interest has emerged in recent years to design novel compound semiconductor materials to fulfill the growing societal needs of efficient light sources, powerful solar cells, miniaturized-electronic-circuitry for lab-on-chip equipment, and a plethora of handheld opto-electronic devices. GaAs-based III-V compounds are significant materials with important fundamental characteristics allowing the scientists and engineers to envision their use in a variety of devices including light-emitting diodes (LEDs), laser diodes (LDs), and high-electron mobility transistors (HEMTs). In this regard, there has been a growing interest of studying the far-infrared optical properties in both un-doped and doped bulk III-V compounds, thin films, ternary alloys, and their nano-structured quantum-wells and superlattices. For GaAs/AlxGa1-xAs materials grown especially by molecular-beam epitaxy (MBE), the optical constants [viz., n, k, N (Charge carrier concentration), R (Reflection), and T (Transmission)] over a broad frequency regime are fundamental inputs that must be known for constructing opto-electronic devices. Despite some success by using Raman Spectroscopy, the influence of free charge carrier concentration on the phonon-plasmon coupled modes (L+/-) by far-infrared (FIR) spectroscopy are still scantily known. Any effort to extract accurate information about the charge carrier concentration N in either n- or p-type doped III-V compounds using FIR would be of significant importance to the scientific community. In this thesis, we will use the electromagnetic theory to study the IR reflectivity and transmission at oblique incidence in both undoped and doped GaAs, AlxGa1-xAs thin films and superlattices in order to correlate the shifts of the L+/- mode frequencies with the free charge carrier concentration. The transmission study in compound semiconductors for s-polarization reveals a single minimum at the resonance frequency of the TO mode, while for p-polarization the transmission minima occur at both the resonance frequencies of the TO and LO modes. In doped semiconductor thin films, the transmission in p-polarization exhibits minima at TO and L+ with a shift of L+ mode to higher frequency as the charge carrier concentration increases.

Rodgers, Robert A.

343

Catalysts based on activated aluminum alloys. I. A study of copper-alumina catalysts by XPS and deuterium-hydrogen exchange  

Microsoft Academic Search

Surface compositions and electron states of elements in copper-containing catalysts prepared by water treatment of copper-aluminum alloys activated by indium and gallium are studied by XPS. The copper contents in the surface layers of the catalysts is found to be less than that in the bulk. Fast isotopic Hâ-Dâ exchange at 70-200°C on reduced copper-containing samples and the absence of

V. I. Yakerson; A. N. Subbotin; B. S. Gudkov; O. P. Tkachenko; R. G. Sarmurzina

1994-01-01

344

Antitumor efficacy and tolerability of systemically administered gallium acetylacetonate-loaded gelucire-stabilized nanoparticles.  

PubMed

The widespread clinical success with most gallium compounds in cancer therapy is markedly hampered by lack of tumor specific accumulation, poor tumor permeability and undesirable toxicity to healthy tissues. The aim of this work was to investigate for the first time antitumor mechanism of a new gallium compound (gallium acetylacetonate; GaAcAc) while assessing effectiveness of gelucire-stabilized nanoparticles (NPs) for potential application in gallium-based lung cancer therapy. NPs loaded with GaAcAc (Ga-NPs) were prepared using mixtures of cetyl alcohol with Gelucire 44/14 (Ga-NP-1) or Gelucire 53/13 (Ga-NP-2) as matrix materials. Of special note from this work is the direct evidence of involvement of microtubule disruption in antitumor effects of GaAcAc on human lung adenocarcinoma (A549). In-vivo tolerability studies were based on plasma ALT, creatinine levels and histopathological examination of tissues. The superior in-vivo antitumor efficacy of Ga-NPs over GaAcAc was depicted in marked reduction of tumor weight and tumor volume as well as histological assessment of excised tumors. Compared to free GaAcAc, Ga-NPs showed a 3-fold increase in tumor-to-blood gallium concentrations with minimized overall exposure to healthy tissues. Overall, enhancement of antitumor effects of GaAcAc by gelucire-stabilized NPs coupled with reduced exposure of healthy tissues to gallium would likely ensure desired therapeutic outcomes and safety of gallium-based cancer treatment. PMID:23858967

Wehrung, Daniel; Bi, Lipeng; Geldenhuys, Werner J; Oyewumi, Moses O

2013-06-01

345

Anodizing of aluminium alloys  

Microsoft Academic Search

Anodizing is used widely in the surface treatment of aluminium alloys for aerospace applications. Considers recent advances in understanding of the influences of alloying elements in anodizing of aluminium alloys and, in particular, their applicability to second phase particles during anodizing of commercial alloys. Through more precise knowledge of the response of second phase materials to anodic polarization, improved anodizing

G. E. Thompson; H. Habazaki; K. Shimizu; M. Sakairi; P. Skeldon; X. Zhou; G. C. Wood

1999-01-01

346

Analytic bond-order potential for the gallium arsenide system D. A. Murdick,* X. W. Zhou, and H. N. G. Wadley  

E-print Network

Analytic bond-order potential for the gallium arsenide system D. A. Murdick,* X. W. Zhou, and H. N An analytic, bond-order potential BOP is proposed and parametrized for the gallium arsenide system.045206 PACS number s : 61.50.Ah, 81.05.Ea, 61.50.Lt I. INTRODUCTION The vapor phase growth of gallium arsenide

Wadley, Haydn

347

Electron and hole capture cross-sections at deep centers in gallium arsenide A. Mitonneau, A. Mircea, G. M. Martin and D. Pons  

E-print Network

853 Electron and hole capture cross-sections at deep centers in gallium arsenide A. Mitonneau, A trap in n-type material. This method has been used to characterize many deep levels in gallium arsenide band gap of the semiconductors. In the particular case of gallium arsenide numerous traps have been

Paris-Sud XI, Université de

348

Stress-induced anisotropy of phosphorous islands on gallium arsenide Chemical Engineering Department, University of CaliforniaLos Angeles, Los Angeles,  

E-print Network

Stress-induced anisotropy of phosphorous islands on gallium arsenide C. H. Li Chemical Engineering growth of 2 4 phosphorous islands on 4 2 terraces of gallium arsenide 001 has been studied. The islands and 48 � in the 1¯10 direction. To compare this to the homoepitaxy of gallium arsenide, we have studied

Li, Lian

349

Nuclear Instruments and Methods in Physics Research A 460 (2001) 207212 Performance of semi-insulating gallium arsenide X-ray pixel  

E-print Network

-insulating gallium arsenide X-ray pixel detectors with current-integrating readout P.J. Sellina, *, G. Rossib , M are presented from tests of a semi-insulating gallium arsenide X-ray imaging detector, flip-chip bonded rights reserved. 1. Introduction We report the first results from a gallium arsenide (GaAs) X-ray imaging

Gruner, Sol M.

350

Gallium in Feldspar Minerals - an Underutilized Source of Petrogenetic Information  

NASA Astrophysics Data System (ADS)

The trace element gallium is routinely analyzed in all kind of rocks. Regardless of this fact it is rarely used as a petrogenetic indicator element. Arguably the best known exception is the discrimination of A-type granites according to the Ga/Al value. Interpreting these data requires our understanding of how Ga is distributed between coexisting crystal phases and liquids. Because of the great importance of the feldspar minerals for the geochemical evolution of Ga a two- step method for Ga analysis of feldspar minerals using the electron microprobe was developed. The first step includes a screening for increased Ga-values during the routine feldspar analyses. A threshold of 100 ppm Ga was used to define 'Ga-rich feldspars'. These feldspars were analyzed for Ga using a special routine with optimized conditions for trace element analysis. To minimize the well known effects of diffusion of alkaline metals and to maintain the high spatial resolution an accelerating voltage of 15 kV was used. In order to improve precision and the lower detection limit long peak counting times of 360 - 600 seconds were chosen. The background curvature and possible interferences of both Ga-K? and Ga-L? lines were studied using standards very poor in gallium. The influence of the beam current on the stability of different feldspar types was tested. In order to ensure the integrity of the sample and the compliance of the analytical task an optimal ratio of beam current to beam diameter has to be chosen for every analysis. Using optimal conditions with low spatial resolution a lower detection limit of 33 ppm was reached. Using this two-step method we found unexpected high Ga values in feldspars of different rock types. Characteristic examples are albite with a Ga-Ca - ratio of > 1 from albite granites in the Central Eastern Desert (Egypt) and zoned plagioclase from mafic microgranular enclaves in granites formed by magma mixing (Karkonosze Mountains in Poland) with Ga-contents greater than 1000 ppm.

Renno, A. D.

2007-12-01

351

Elimination of arthritis pain and inflammation for over 2 years with a single 90 min, topical 14% gallium nitrate treatment: case reports and review of actions of gallium III.  

PubMed

Arthritis is inflammation in a joint often with joint damage, usually accompanied by pain, swelling and stiffness, resulting from infection, trauma, degenerative changes, metabolic disturbances, autoimmune or other causes. It occurs in various forms, including rheumatoid arthritis, osteoarthritis, bacterial arthritis and gout. Gallium III can inhibit the production of inflammatory cytokines, such as IL-1beta, produced by macrophage-like cells in vitro. A dose-dependent inhibition of IL-1beta and TPA stimulated MMP activity by gallium nitrate at increasing concentrations occurs, demonstrating that gallium nitrate can be a useful modulator of inflammation in arthritis. Gallium III is an inhibitor of bone resorption and is an effective treatment for hypercalcemia. Gallium III has been reported to be effective in the treatment of mycobacterium butycicum-induced arthritis in rats by antagonism of iron III. Long-term elimination of pain from arthritis by gallium III was first observed in horses primarily being treated for navicular disease. Several people treating their horses with gallium nitrate coincidentally found that arthritis pain in their fingers ended and did not return after soaking their hands in 14% gallium nitrate solution. Therefore, the severely arthritic hands of a 60-year-old woman were topically treated with a 14% aqueous solution of gallium nitrate for 90 min. Pain and inflammation from rheumatoid arthritis diminished rapidly, and neither pain nor inflammation returned during the following 2 years from that single treatment. A 61-year-old woman who had osteoarthritis in her left knee, shoulders and wrists was treated orally with 50 ml of a 1% gallium nitrate solution (120 mg elemental gallium) daily using a two week on and two week off protocol, resulting in almost total elimination of pain while on gallium nitrate, while pain partially returned during the two week off periods. Treatment of frozen shoulder with topical 40% gallium nitrate for 120 min resulted in greatly reduced pain and crepitus almost immediately with complete restoration of range of motion, with pain remaining essentially absent for over 1 year. Mechanisms of action are hypothesized to include anti-inflammatory, bone density improvements, antibacterial, anti-iron III and anti-aluminum III effects. Proper use of gallium III may be effective in terminating pain and inflammation of arthritis for years, often with a single treatment. PMID:16122880

Eby, George

2005-01-01

352

Gallium-mediated siderophore quenching as an evolutionarily robust antibacterial treatment  

PubMed Central

Background and objectives: Conventional antibiotics select strongly for resistance and are consequently losing efficacy worldwide. Extracellular quenching of shared virulence factors could represent a more promising strategy because (i) it reduces the available routes to resistance (as extracellular action precludes any mutations blocking a drug’s entry into cells or hastening its exit) and (ii) it weakens selection for resistance, as fitness benefits to emergent mutants are diluted across all cells in a cooperative collective. Here, we tested this hypothesis empirically. Methodology: We used gallium to quench the iron-scavenging siderophores secreted and shared among pathogenic Pseudomonas aeruginosa bacteria, and quantitatively monitored its effects on growth in vitro. We assayed virulence in acute infections of caterpillar hosts (Galleria mellonella), and tracked resistance emergence over time using experimental evolution. Results: Gallium strongly inhibited bacterial growth in vitro, primarily via its siderophore quenching activity. Moreover, bacterial siderophore production peaked at intermediate gallium concentrations, indicating additional metabolic costs in this range. In vivo, gallium attenuated virulence and growth—even more so than in infections with siderophore-deficient strains. Crucially, while resistance soon evolved against conventional antibiotic treatments, gallium treatments retained their efficacy over time. Conclusions: Extracellular quenching of bacterial public goods could offer an effective and evolutionarily robust control strategy. PMID:24480613

Ross-Gillespie, Adin; Weigert, Michael; Brown, Sam P.; Kummerli, Rolf

2014-01-01

353

Cleansing the colon in gallium-67 scintigraphy: a prospective comparison of regimens  

SciTech Connect

Colonic accumulation of gallium-67 frequently complicates the interpretation of gallium-67 scintigrams. Although various modes of cleansing the colon prior to scintigraphy have been suggested, there is controversy over their efficacy and none have been tested prospectively. Three hundred nine patients undergoing gallium-67 scintigraphy were randomly assigned to one of four cleansing regimens: (1) a high fiber diet (78 patients); (2) castor oil (76); (3) milk of magnesia and cascara (76); and (4) no preparation (79). Patient compliance rates for the four regimens were 17%, 32%, 36%, and 46%, respectively. After noncompliant patients were excluded, gallium-67 scintigrams were graded for colonic activity on a scale of 0-3 by three independent, experienced observers. Gallium-67 activity in the colon was significantly less after adminstration of castor oil than after no prepartion (p = 0.083). Regimen 3 did not produce significantly better results than regimen 4 (p = 0.42). A major impediment to the success of any cleansing regimen seems to be poor compliance of patients.

Novetsky, G.J.; Turner, D.A.; Ali, A.; Raynor, W.J.; Fordham, E.W.

1981-11-01

354

Cleansing the colon in gallium-67 scintigraphy: a prospective comparison of regimens  

SciTech Connect

Colonic accumulation of gallium-67 frequently complicates the interpretation of gallium-67 scintigrams. Although various modes of cleansing the colon prior to scintigraphy have been suggested, there is controversy over their efficacy and none have been tested prospectively. Three hundred nine patients undergoing gallium-67 scintigraphy were randomly assigned to one of four cleansing regimens: (1) a high fiber diet (78 patients); (2) castor oil (76); (3) milk of magnesia and cascara (76); and (4) not preparation (79). Patient compliance rates for the four regimens were 17%, 32%, 36%, and 46%, respectively. After noncompliant patients were excluded, gallium-67 scintigrams were graded for colonic activity on a scale of 0-3 by three independent, experienced observers. Gallium-67 activity in the colon was significantly less after administration of castor oil than after no preparation (p . 0.047). A high fiber diet also resulted in a substantial reduction of colonic activity when compared with no preparation; the difference, however, was not statistically significant (p . 0.083). Regimen 3 did not produce significantly better results than regimen 4 (p . 0.42). A major impediment to the success of any cleansing regimen seems to be poor compliance of patients.

Novetsky, G.J.; Turner, D.A.; Ali, A.; Raynor, W.J. Jr.; Fordham, E.W.

1981-01-01

355

A novel active area bumped flip chip technology for convergent heat transfer from gallium arsenide power devices  

Microsoft Academic Search

Superior low noise amplification characteristics have made gallium arsenide power amplifiers attractive for consumer electronics applications, e.g., cellular phones. To reduce the cost of their introduction, many new technical approaches are being pursued in the areas of device design, fabrication, and even packaging. The difficulty in dissipating heat from conventionally die bonded\\/wire bonded gallium arsenide power amplifiers forces thinning of

D. Gupta

1995-01-01

356

Capillary-wave roughening of surface-induced layering in liquid gallium M. J. Regan and P. S. Pershan  

E-print Network

Capillary-wave roughening of surface-induced layering in liquid gallium M. J. Regan and P. S 11 June 1996 The temperature dependence of surface-induced atomic layering in liquid gallium has been to the temperature dependence of capillary-wave induced surface roughness. The constant width indicates a temperature

Pershan, Peter S.

357

Low temperature spin glass transition in Gallium ferrite single crystals  

NASA Astrophysics Data System (ADS)

Magnetoelectric gallium ferrite (GaFeO3 or GFO) manifests close to room temperature ferrimagnetism owing to inherent cationic site disorder in an otherwise antiferromagnetic ground state structure. In GFO, Fe ions at Fe1 and Fe2 sites are antiferromagnetically coupled while Fe and Ga at Fe2 and Ga2 sites respectively are ferromagnetically coupled. Ga1 site is magnetically inactive. Here, we present a detailed study to probe phase transitions in GFO using ac and dc magnetic characterization methods to demonstrate spin glass behavior in GFO below 200 K. Our dc magnetization measurement exhibits that while GFO undergoes standard para (PM) to ferromagnetic (fM) transition at Tc ˜ 290 K, splitting between field cooled and zero-field cooled plots is observed at low temperatures hinting at the spin-glass like behavior. Further, temperature dependent ac susceptibility measurements at different frequencies and at different dc fields demonstrate that the system exhibits a non-equilibrium canonical spin glass (SG) state below the spin glass transition temperature ˜ 210 K. The spin glass state has been further characterized by memory effect and aging measurements. The origin of such a spin-glass phase is proposed to arise from a network of geometrically frustrated spin system attributed to combination of antiferromagnetic interaction among the Fe ions in the two Fe sites and Ga2 site as well as inherent cation site disorder.

Mukherjee, Somdutta; Gupta, Rajeev; Garg, Ashish

2012-02-01

358

Hydrogenation of palladium rich compounds of aluminium, gallium and indium  

SciTech Connect

Palladium rich intermetallic compounds of aluminium, gallium and indium have been studied before and after hydrogenation by powder X-ray diffraction and during hydrogenation by in situ thermal analysis (DSC) at hydrogen gas pressures up to 39 MPa and temperatures up to 700 K. Very weak DSC signals and small unit cell increases of below 1% for AlPd{sub 2}, AlPd{sub 3}, GaPd{sub 2}, Ga{sub 5}Pd{sub 13}, In{sub 3}Pd{sub 5}, and InPd{sub 2} suggest negligible hydrogen uptake. In contrast, for both tetragonal modifications of InPd{sub 3} (ZrAl{sub 3} and TiAl{sub 3} type), heating to 523 K at 2 MPa hydrogen pressure leads to a rearrangement of the intermetallic structure to a cubic AuCu{sub 3} type with an increase in unit cell volume per formula unit by 3.6-3.9%. Gravimetric analysis suggests a composition InPd{sub 3}H{sub a}pprox{sub 0.8} for the hydrogenation product. Very similar behaviour is found for the deuteration of InPd{sub 3}. - Graphical abstract: In situ differential scanning calorimetry of the hydrogenation of tetragonal InPd{sub 3} (ZrAl{sub 3} type) at 1.3 MPa hydrogen pressure.

Kohlmann, H., E-mail: h.kohlmann@mx.uni-saarland.d [Saarland University, Inorganic Solid State Chemistry, Saarbruecken (Germany)

2010-02-15

359

Isolation and characterization of gallium resistant Pseudomonas aeruginosa mutants.  

PubMed

Pseudomonas aeruginosa PA14 cells resistant to the novel antimicrobial gallium nitrate (Ga) were developed using transposon mutagenesis and by selecting spontaneous mutants. The mutants showing the highest growth in the presence of Ga were selected for further characterization. These mutants showed 4- to 12-fold higher Ga minimal inhibitory growth concentrations and a greater than 8-fold increase in the minimum biofilm eliminating Ga concentration. Both types of mutants produced Ga resistant biofilms whereas the formation of wild-type biofilms was strongly inhibited by Ga. The gene interrupted in the transposon mutant was hitA, which encodes a periplasmic iron binding protein that delivers Fe³? to the HitB iron permease; complementation of the mutant with the hitA gene restored the Ga sensitivity. This hitA mutant showed a 14-fold decrease in Ga internalization versus the wild-type strain, indicating that the HitAB system is also involved in the Ga uptake. Ga uptake in the spontaneous mutant was also lower, although no mutations were found in the hitAB genes. Instead, this mutant harbored 64 non-silent mutations in several genes including those of the phenazine pyocyanin biosynthesis. The spontaneous mutant produced 2-fold higher pyocyanin basal levels than the wild-type; the addition of this phenazine to wild-type cultures protected them from the Ga bacteriostatic effect. The present data indicate that mutations affecting Ga transport and probably pyocyanin biosynthesis enable cells to develop resistance to Ga. PMID:23992635

García-Contreras, Rodolfo; Lira-Silva, Elizabeth; Jasso-Chávez, Ricardo; Hernández-González, Ismael L; Maeda, Toshinari; Hashimoto, Takahiro; Boogerd, Fred C; Sheng, Lili; Wood, Thomas K; Moreno-Sánchez, Rafael

2013-12-01

360

Packaging of an iron-gallium (Galfenol) nanowire acoustic sensor  

NASA Astrophysics Data System (ADS)

Packaging is a key issue for the effective working of an iron-gallium (Galfenol) nanowire acoustic sensor for underwater applications. The nanowire acoustic sensor incorporates cilia-like nanowires made of galfenol, a magnetostrictive material, which responds by changing magnetic flux flowing through it due to bending stress induced by the incoming acoustic waves. This stress induced change in the magnetic flux density is detected by a GMR sensor. An effective package should provide a suitably protective environment to these nanowires, while allowing sound waves to reach the nanowires with a minimum level of attenuation. A bio-inspired MEMS package has been designed, analogous to a human-ear cochlea for the nanowire acoustic sensor. In this paper, the process sequence for fabrication of the package is presented. Unlike other microphones, the nanoacoustic sensor has been enclosed in a cavity to allow free movement of the nanowires in a fluid medium. The package also ensures resisting ingression of sea water and salt ions to prevent the corrosion of sensor components. The effect of package material on sensor performance was investigated by conducting experiments on acoustic impedance and attenuation characteristics, and salt water absorption properties. The package filled with silicone oil and molded with polydimethylsiloxane (PDMS) is observed to outperform other packages at all frequencies by minimizing attenuation of the acoustic waves.

Jain, Rupal; McCluskey, F. Patrick; Flatau, Alison B.; Stadler, Bethanie J. H.

2007-04-01

361

Gallium-67 lung uptake: conjugate-view technique.  

PubMed

A conjugate-view technique is derived for calculation of absolute gallium-67 (Ga-67) uptake from scintillation-camera images. The technique combines counts of posterior and anterior images of the lung with an attenuation correction obtained from cobalt-57 (Co-57) transmission imaging. The formulation is such that the effects of Compton scatter build-up are accounted for. Studies utilizing a canine model indicated that, normally, more activity is located in the chest wall than in the lungs. The quantitative technique must therefore accurately account for a variety of Ga-67 distributions, including that in the chest wall. Calculations were performed using a three-component model comparing results obtained with the conjugate-view approach to the actual uptake. These calculations suggest that an assumption of uniform activity distribution allows an accuracy of approximately +/- 10% over a broad range of body-part thicknesses and uptake by the lungs. It was concluded that the conjugate-view technique is necessarily approximate but can provide clinically useful results. PMID:4059564

Grossman, L W; Fernandez-Ulloa, M; Lukes, S J; Mantil, J

1985-12-01

362

Gallium arsenide deep-level optical emitter for fibre optics.  

PubMed

Fibre-optic components fabricated on the same substrate as integrated circuits are important for future high-speed communications. One industry response has been the costly push to develop indium phosphide (InP) electronics. However, for fabrication simplicity, reliability and cost, gallium arsenide (GaAs) remains the established technology for integrated optoelectronics. Unfortunately, the GaAs bandgap wavelength (0.85 microm) is far too short for fibre optics at 1.3-1.5 microm. This has led to work on materials that have a large lattice mismatch on GaAs. Here we demonstrate the first light-emitting diode (LED) that emits at 1.5 microm fibre-optic wavelengths in GaAs using optical transitions from arsenic antisite (As(Ga)) deep levels. This is an enabling technology for fibre-optic components that are lattice-matched to GaAs integrated circuits. We present experimental results showing significant internal optical power (24 mW) and speed (in terahertz) from GaAs optical emitters using deep-level transitions. Finally, we present theory showing the ultimate limit to the efficiency-bandwidth product of semiconductor deep-level optical emitters. PMID:12738958

Pan, Janet L; McManis, Joseph E; Osadchy, Thomas; Grober, Louise; Woodall, Jerry M; Kindlmann, Peter J

2003-06-01

363

Gallium arsenide deep-level optical emitter for fibre optics  

NASA Astrophysics Data System (ADS)

Fibre-optic components fabricated on the same substrate as integrated circuits are important for future high-speed communications. One industry response has been the costly push to develop indium phosphide (InP) electronics. However, for fabrication simplicity, reliability and cost, gallium arsenide (GaAs) remains the established technology for integrated optoelectronics. Unfortunately, the GaAs bandgap wavelength (0.85 ?m) is far too short for fibre optics at 1.3-1.5 ?m. This has led to work on materials that have a large lattice mismatch on GaAs. Here we demonstrate the first light-emitting diode (LED) that emits at 1.5 ?m fibre-optic wavelengths in GaAs using optical transitions from arsenic antisite (AsGa) deep levels. This is an enabling technology for fibre-optic components that are lattice-matched to GaAs integrated circuits. We present experimental results showing significant internal optical power (24 mW) and speed (in terahertz) from GaAs optical emitters using deep-level transitions. Finally, we present theory showing the ultimate limit to the efficiency-bandwidth product of semiconductor deep-level optical emitters.

Pan, Janet L.; McManis, Joseph E.; Osadchy, Thomas; Grober, Louise; Woodall, Jerry M.; Kindlmann, Peter J.

2003-06-01

364

Gallium Arsenide (GaAs) Quantum Photonic Waveguide Circuits  

E-print Network

Integrated quantum photonics is a promising approach for future practical and large-scale quantum information processing technologies, with the prospect of on-chip generation, manipulation and measurement of complex quantum states of light. The gallium arsenide (GaAs) material system is a promising technology platform, and has already successfully demonstrated key components including waveguide integrated single-photon sources and integrated single-photon detectors. However, quantum circuits capable of manipulating quantum states of light have so far not been investigated in this material system. Here, we report GaAs photonic circuits for the manipulation of single-photon and two-photon states. Two-photon quantum interference with a visibility of 94.9 +/- 1.3% was observed in GaAs directional couplers. Classical and quantum interference fringes with visibilities of 98.6 +/- 1.3% and 84.4 +/- 1.5% respectively were demonstrated in Mach-Zehnder interferometers exploiting the electro-optic Pockels effect. This w...

Wang, Jianwei; Jiang, Pisu; Bonneau, Damien; Engin, Erman; Silverstone, Joshua W; Lermer, Matthias; Beetz, Johannes; Kamp, Martin; Hofling, Sven; Tanner, Michael G; Natarajan, Chandra M; Hadfield, Robert H; Dorenbos, Sander N; Zwiller, Val; O'Brien, Jeremy L; Thompson, Mark G

2014-01-01

365

Deprotecting Thioacetyl-Terminated Terphenyldithiol for Assembly on Gallium Arsenide  

SciTech Connect

We characterize the assembly of terphenyldithiol (TPDT) on gallium arsenide (GaAs) from ethanol (EtOH) and tetrahydrofuran (THF) as a function of ammonium hydroxide (NH4OH) concentration. NH4OH facilitates the conversion of thioacetyl end groups of the TPDT precursor to thiolates in the assembly solution. The final structure of TPDT assembled on GaAs is sensitive not only to the assembly solvent but also to NH4OH concentration. In the presence of low concentrations of NH4OH (1 mM), TPDT assemblies from EtOH are oriented upright. The same assemblies are less upright when adsorption is carried out at higher NH4OH concentrations. In THF, TPDT does not adsorb significantly on GaAs at low NH4OH concentrations. The surface coverage and structural organization of these assemblies improve with increasing NH4OH concentrations, although these assemblies are never as organized as those from EtOH. The difference in the final structure of TPDT assemblies is attributed to differences in the thiolate fraction in the assembly solution at the point of substrate immersion.

Krapchetov,D.; Ma, H.; Jen, A.; Fischer, D.; Loo, Y.

2008-01-01

366

Gallium Arsenide (GaAs) Quantum Photonic Waveguide Circuits  

E-print Network

Integrated quantum photonics is a promising approach for future practical and large-scale quantum information processing technologies, with the prospect of on-chip generation, manipulation and measurement of complex quantum states of light. The gallium arsenide (GaAs) material system is a promising technology platform, and has already successfully demonstrated key components including waveguide integrated single-photon sources and integrated single-photon detectors. However, quantum circuits capable of manipulating quantum states of light have so far not been investigated in this material system. Here, we report GaAs photonic circuits for the manipulation of single-photon and two-photon states. Two-photon quantum interference with a visibility of 94.9 +/- 1.3% was observed in GaAs directional couplers. Classical and quantum interference fringes with visibilities of 98.6 +/- 1.3% and 84.4 +/- 1.5% respectively were demonstrated in Mach-Zehnder interferometers exploiting the electro-optic Pockels effect. This work paves the way for a fully integrated quantum technology platform based on the GaAs material system.

Jianwei Wang; Alberto Santamato; Pisu Jiang; Damien Bonneau; Erman Engin; Joshua W. Silverstone; Matthias Lermer; Johannes Beetz; Martin Kamp; Sven Hofling; Michael G. Tanner; Chandra M. Natarajan; Robert H. Hadfield; Sander N. Dorenbos; Val Zwiller; Jeremy L. O'Brien; Mark G. Thompson

2014-03-11

367

Enhanced photothermal conversion in vertically oriented gallium arsenide nanowire arrays.  

PubMed

The photothermal properties of vertically etched gallium arsenide nanowire arrays are examined using Raman spectroscopy. The nanowires are arranged in square lattices with a constant pitch of 400 nm and diameters ranging from 50 to 155 nm. The arrays were illuminated using a 532 nm laser with an incident energy density of 10 W/mm(2). Nanowire temperatures were highly dependent on the nanowire diameter and were determined by measuring the spectral red-shift for both TO and LO phonons. The highest temperatures were observed for 95 nm diameter nanowires, whose top facets and sidewalls heated up to 600 and 440 K, respectively, and decreased significantly for the smaller or larger diameters studied. The diameter-dependent heating is explained by resonant coupling of the incident laser light into optical modes of the nanowires, resulting in increased absorption. Photothermal activity in a given nanowire diameter can be optimized by proper wavelength selection, as confirmed using computer simulations. This demonstrates that the photothermal properties of GaAs nanowires can be enhanced and tuned by using a photonic lattice structure and that smaller nanowire diameters are not necessarily better to achieve efficient photothermal conversion. The diameter and wavelength dependence of the optical coupling could allow for localized temperature gradients by creating arrays which consist of different diameters. PMID:25233265

Walia, Jaspreet; Dhindsa, Navneet; Flannery, Jeremy; Khodabad, Iman; Forrest, James; LaPierre, Ray; Saini, Simarjeet S

2014-10-01

368

Formation of gallium arsenide nanostructures in Pyrex glass.  

PubMed

In this paper, we report on a simple, low-cost process to grow GaAs nanostructures of a few nm diameter and ?50 nm height in Pyrex glass wafers. These nanostructures were grown by sequential plasma activation of GaAs and Pyrex glass surfaces using a low-temperature hybrid plasma bonding technology in air. Raman analyses of the activated surfaces show gallium oxide and arsenic oxide, as well as suppressed non-bridging oxygen with aluminate and boroxol chains in glass. The flow of alkaline ions toward the cathode and the replacement of alkaline ions by Ga and As ions in glass result in the growth of GaAs nanostructures in nanopores/nanoscratches in glass. These nanopores/nanoscratches are believed to be the origin of the growth of the nanostructures. It was found that the length of the GaAs nanostructures may be controlled by an electrostatic force. Cross-sectional observation of the bonded interface using high-resolution transmission electron microscopy confirms the existence of the nanostructures. A possible application of the nanostructures in glass is a filtration system for biomolecules. PMID:23857990

Howlader, Matiar M R; Zhang, Fangfang; Deen, M Jamal

2013-08-01

369

Low-temperature thermal conductivity of terbium-gallium garnet  

SciTech Connect

Thermal conductivity of paramagnetic Tb{sub 3}Ga{sub 5}O{sub 12} (TbGG) terbium-gallium garnet single crystals is investigated at temperatures from 0.4 to 300 K in magnetic fields up to 3.25 T. A minimum is observed in the temperature dependence {kappa}(T) of thermal conductivity at T{sub min} = 0.52 K. This and other singularities on the {kappa}(T) dependence are associated with scattering of phonons from terbium ions. The thermal conductivity at T = 5.1 K strongly depends on the magnetic field direction relative to the crystallographic axes of the crystal. Experimental data are considered using the Debye theory of thermal conductivity taking into account resonance scattering of phonons from Tb{sup 3+} ions. Analysis of the temperature and field dependences of the thermal conductivity indicates the existence of a strong spin-phonon interaction in TbGG. The low-temperature behavior of the thermal conductivity (field and angular dependences) is mainly determined by resonance scattering of phonons at the first quasi-doublet of the electron spectrum of Tb{sup 3+} ion.

Inyushkin, A. V., E-mail: inyushkin@imp.kiae.ru; Taldenkov, A. N. [Kurchatov Institute, Russian Research Centre (Russian Federation)

2010-11-15

370

Low-temperature thermal conductivity of terbium-gallium garnet  

NASA Astrophysics Data System (ADS)

Thermal conductivity of paramagnetic Tb3Ga5O12 (TbGG) terbium-gallium garnet single crystals is investigated at temperatures from 0.4 to 300 K in magnetic fields up to 3.25 T. A minimum is observed in the temperature dependence ?( T) of thermal conductivity at T min = 0.52 K. This and other singularities on the ?( T) dependence are associated with scattering of phonons from terbium ions. The thermal conductivity at T = 5.1 K strongly depends on the magnetic field direction relative to the crystallographic axes of the crystal. Experimental data are considered using the Debye theory of thermal conductivity taking into account resonance scattering of phonons from Tb3+ ions. Analysis of the temperature and field dependences of the thermal conductivity indicates the existence of a strong spin-phonon interaction in TbGG. The low-temperature behavior of the thermal conductivity (field and angular dependences) is mainly determined by resonance scattering of phonons at the first quasi-doublet of the electron spectrum of Tb3+ ion.

Inyushkin, A. V.; Taldenkov, A. N.

2010-11-01

371

Accurate quantification of radioactive materials by x-ray fluorescence : gallium in plutonium metal /.  

SciTech Connect

Two XRF specimen preparation methods were investigated for quantifying gallium in plutonium metal. Gallium in plutonium was chosen here as an example for demonstrating the efficacy of wavelength dispersive XRF for quantifying radioactive materials. The steps necessary to handle such materials safely will also be discussed. Quantification of plutonium samples by a well-established aqueous specimen preparation method resulted in relative precision and accuracy values of well less than 1%. As an alternative to the aqueous approach, a dried residue method was studied. Quantification of gallium in samples using this method resulted in relative precision and accuracy values an order of magnitude worse, but the method is faster, safer, and generates less waste than the aqueous process. The specimen preparation details and analysis results using each method will be presented here.

Worley, C. G. (Christopher G.)

2002-01-01

372

High resolution measurement of the carbon localized vibrational mode in gallium arsenide  

SciTech Connect

The localized vibrational mode of carbon substituted at arsenic sites in gallium arsenide (GaAs) was measured with infrared absorption spectroscopy at 0.005 cm{sup {minus}1} resolution. Well-resolved fine structures were observed, yielding quantitative information on the line half widths and intensities. The relative intensities of the isotope lines are well fitted to a probability factor calculation using a natural abundance of 55.3% {sup 69}Ga. One explanation considered is that the dipole moment due to the relative displacement of carbon with respect to the gallium atoms has a tendency to be larger when the neighboring gallium atoms are heavier ({sup 71}Ga). {copyright} 2001 American Institute of Physics.

Nagai, Naoto

2001-06-15

373

Piecewise simulaton proton test of gallium arsenide and thin silicon solar cells  

NASA Technical Reports Server (NTRS)

Gallium Arsenide (GaAs) solar cells are viewed as a potential primary power source on certain future Earth orbiting satellites. However, the relative merits of gallium arsenide over silicon in a space radiation environment are largely unknown because a general degradation model for gallium arsenide does not exist. The results of a test simulating the proton radiation environment existing in a polar orbit and the concomitant effects on GaAs and thin silicon (Si) solar cells are presented. The objectives and methodology of the simulation test were discussed. The electrical characteristics of GaAs and Si solar cells are given in graph form. It was concluded that GaAs cells are viable for use on satellites in low Earth orbit.

Peterson, D. G.; Billets, S. A.

1984-01-01

374

Thin film gallium arsenide solar cell research. Final report, 1 March-31 August 1982 and 1 May 1983-31 March 1984  

SciTech Connect

This report contains results of research conducted to produce thin-film gallium arsenide solar cells of 12% conversion efficiency from films 5 to 10 ..mu..m thick deposited on low-cost substrates by chemical vapor deposition. Major efforts during this reporting period were directed to the fabrication and characterization of thin-film gallium arsenide solar cells, the fabrication and characterization of gallium aluminum arsenide/gallium arsenide heterojunction solar cells, the preparation of Ge/Si substrates, the recrystallization of germanium films on foreign substrates, and the fabrication and characterization of homojunction solar cells with large-grain gallium arsenide films.

Chu, S.S.

1984-10-01

375

Crystal chemistry and self-lubricating properties of monochalcogenides gallium selenide and tin selenide  

SciTech Connect

This paper describes the fundamentals of the crystal chemistry and self-lubricating mechanisms of two monochalcogenides; tin selenide and gallium selenide. Specifically, it enumerates their inter-atomic array and bond structure in crystalline states, and correlates this fundamental knowledge with their self-lubricating capacity. Friction tests assessing the self-lubricating performance of gallium and tin selenides were carried out on a pin-on-disk machine. Specifically, large crystalline pieces of gallium selenide and tin selenide were cut and cleaved into flat squares and subsequently rubbed against the sapphire balls. In another case, the fine powders (particle size {approx} 50--100 {mu}m) of gallium selenide and tin selenide were manually fed into the sliding interfaces of 440C pins and 440C disks. For the specific test conditions explored, it was found that the friction coefficients of the sapphire/gallium selenide and sapphire/tin selenide pairs were {approx} 0.23 and {approx} 0.35, respectively. The friction coefficients of 440C pin/440C disk test pairs with gallium selenide and tin selenide powders were on the orders of {approx} 0.22 and {approx} 0.38, respectively. For comparison, a number of parallel friction tests were performed with MoS{sub 2} powders and compacts and the results of these tests were also reported. The friction data together with the crystal-chemical knowledge and the electron microscopic evidence supported the conclusion that the lubricity and self-lubricating mechanisms of these solids are closely related to their crystal chemistry and the nature of interlayer bonding.

Erdemir, A.

1993-02-01

376

Effect of novel antibacterial gallium-carboxymethyl cellulose on Pseudomonas aeruginosa.  

PubMed

Gallium has emerged as a new therapeutic agent due partly to the scarcity in development of new antibiotics. In this study, a novel antibacterial gallium exchanged carboxymethyl cellulose (Ga-CMC) has been developed and tested for the susceptibility on a common bacteria, Pseudomonas aeruginosa. The results show that an increase in average molecular weight (MW) from 90 k, 250 k to 700 k of Ga-CMC caused a decrease in antimicrobial activity against planktonic P. aeruginosa. Gallium loading of the Ga-CMC (250 k) samples was altered by varying the amount of functionality (0.7, 0.9 and 1.2 acid groups per mole of carbohydrate) which affected also its antimicrobial activity against planktonic P. aeruginosa. Further, the ability to prevent the growth of biofilms of P. aeruginosa was tested on MW = 250 k samples with 0.9 acid groups per mole of carbohydrate as this sample showed the most promising activity against planktonic P. aeruginosa. Gallium was found to reduce biofilm growth of P. aeruginosa with a maximum effect (0.85 log(10) CFU reduction compared to sodium-carboxymethyl cellulose, Na-CMC) after 24 h. Results of the solubility and ion exchange studies show that this compound is suitable for the controlled release of Ga(3+) upon their breakdown in the presence of bacteria. SEM EDX analysis confirmed that Ga(3+) ions are evenly exchanged on the cellulose surface and systematic controls were carried out to ensure that antibacterial activity is solely due to the presence of gallium as samples intrinsic acidity or nature of counterion did not affect the activity. The results presented here highlight that Ga-CMC may be useful in controlled drug delivery applications, to deliver gallium ions in order to prevent infections due to P. aeruginosa biofilms. PMID:23165321

Valappil, Sabeel P; Yiu, Humphrey H P; Bouffier, Laurent; Hope, Christopher K; Evans, Gary; Claridge, John B; Higham, Susan M; Rosseinsky, Matthew J

2013-02-01

377

Novel ethylenediamine-gallium phosphate containing 6-fold coordinated gallium atoms with unusual four equatorial Ga-N bonds  

NASA Astrophysics Data System (ADS)

A novel ethylenediamine-gallium phosphate, formulated as Ga(H2NCH2CH2NH2)2PO4·2H2O, was synthesized under hydrothermal conditions. The crystal structure, including hydrogen positions, was determined using single-crystal X-ray diffraction data (monoclinic, a=9.4886(3) Å, b=6.0374(2) Å, c=10.2874(3) Å, and ?=104.226(3)°, space group Pc) and the bulk was characterized by chemical (Ga-P-C-H-N) and thermal analysis (TG-MS and DSC), including activation energy data of its thermo-oxidative degradation, powder X-ray diffraction (PXRD), solid-state nuclear magnetic resonance (SS-NMR) measurements, and transmission electron microscopy (TEM, SAED/NBD, and STEM BF-EDX). The crystal structure is built up of infinite zig-zag chains running along the c-axis, formed by vertex-shared {PO4} and {GaO2N4} polyhedra. The new compound is characterized by unusual four equatorial Ga-N bonds coming from two nonequivalent ethylenediamine molecules and exhibits strong blue emission at 430 nm (?ex=350 nm) in the solid state at room temperature.

Torre-Fernández, Laura; Espina, Aránzazu; Khainakov, Sergei A.; Amghouz, Zakariae; García, José R.; García-Granda, Santiago

2014-07-01

378

Gallium- and iodine-co-doped titanium dioxide for photocatalytic degradation of 2-chlorophenol in aqueous solution: Role of gallium  

NASA Astrophysics Data System (ADS)

Visible-light-driven TiO2-based catalysts for the degradation of pollutants have become the focus of attention. In the present work, iodine-doped titania photocatalysts (I-TiO2) were improved by doping with gallium (Ga,I-TiO2) and the resulting physicochemical properties and photocatalytic activity were investigated. The structural properties of the catalysts were determined by X-ray diffraction, UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis and transmission electron microscopy. We found that Ga probably enters the TiO2 framework for doping levels <0.5 mol%. A further increase in Ga content probably leads to dispersal of excess Ga on the TiO2 surface. The photocatalytic activity of Ga,I-TiO2 catalysts was evaluated using 2-chlorophenol (2-CP) as a model compound under visible and UV-vis light irradiation. The results indicate that 0.5 mol% Ga loading and calcination at 400 °C represent optimal conditions in the calcining temperature range 400-600 °C and with doping levels from 0.1% to 1 mol%. The effective enhancement of 2-CP degradation might be attributed to the formation of oxygen vacancies by Ga doping, which could decrease the recombination of electron-hole pairs.

Song, Shuang; Wang, Cheng; Hong, Fangyue; He, Zhiqiao; Cai, Qiaolan; Chen, Jianmeng

2011-02-01

379

Gallium diffusion into self-assembled InAs quantum dots grown on indium phosphide substrates  

SciTech Connect

The photoluminescence spectrum of small self-assembled In(Ga)As quantum dots grown on InP substrates is composed of distinct spectral lines. These lines correspond to monolayer variations in the dots smallest dimension: their heights. We use this phenomenon in order to study the diffusion of gallium atoms into the self-assembled quantum dots. We demonstrate that substantial amounts of gallium atoms diffuse from a strained GaInP layer underneath the quantum dots into the quantum dots.

Raz, T.; Shuall, N.; Bahir, G.; Ritter, D.; Gershoni, D.; Chu, S.N.G. [Department of Electrical Engineering, Technion - Israel Institute of Technology, Technion City, Haifa 32000 (Israel); Physics Department and The Solid State Institute, Technion - Israel Institute of Technology, Technion City, Haifa 32000 (Israel); Multiplex, Inc., 5000 Hadley Rd., South Plainfield, New Jersey 07080 (United States)

2004-10-18

380

A 9 keV electron-impact liquid-gallium-jet x-ray source  

Microsoft Academic Search

We demonstrate a high-brightness compact 9 keV electron-impact microfocus x-ray source based on a liquid-gallium-jet anode. A ~30 W, 50 kV electron gun is focused onto the ~20 m\\/s, 30 mum diameter liquid-gallium-jet anode to produce an ~10 mum full width at half maximum x-ray spot. The peak spectral brightness is >2×1010 photons\\/(s mm2 mrad2×0.1% BW). Calculation and experiments show

M. Otendal; T. Tuohimaa; U. Vogt; H. M. Hertz

2008-01-01

381

Gallium compounds in solar cells. (Latest citations from the Aerospace database). Published Search  

SciTech Connect

The bibliography contains citations concerning the use of gallium compounds in solar cells to increase solar cell efficiency. Computer models, theories, and performance tests are included. Gallium compounds used in thin film cells, cascade solar cells, large area solar cells, cells designed for industrial and space applications, and as antireflection coatings are discussed. Resistance to radiation damage, cooling to improve efficiency, grain boundary behavior, and economic considerations are also covered. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1996-01-01

382

Gallium-SPECT in the detection of prosthetic valve endocarditis and aortic ring abscess  

SciTech Connect

A 52-yr-old man who had a bioprosthetic aortic valve developed Staphylococcus aureus bacteremia. Despite antibiotic therapy he had persistent pyrexia and developed new conduction system disturbances. Echocardiography did not demonstrate vegetations on the valve or an abscess, but gallium scintigraphy using SPECT clearly identified a focus of intense activity in the region of the aortic valve. The presence of valvular vegetations and a septal abscess was confirmed at autopsy. Gallium scintigraphy, using SPECT, provided a useful noninvasive method for the demonstration of endocarditis and the associated valve ring abscess.

O'Brien, K.; Barnes, D.; Martin, R.H.; Rae, J.R. (Department of Diagnostic Radiology, Victoria General Hospital Halifax, Nova Scotia (Canada))

1991-09-01

383

Thermal Cycling and High Temperature Reverse Bias Testing of Control and Irradiated Gallium Nitride Power Transistors  

NASA Technical Reports Server (NTRS)

The power systems for use in NASA space missions must work reliably under harsh conditions including radiation, thermal cycling, and exposure to extreme temperatures. Gallium nitride semiconductors show great promise, but information pertaining to their performance is scarce. Gallium nitride N-channel enhancement-mode field effect transistors made by EPC Corporation in a 2nd generation of manufacturing were exposed to radiation followed by long-term thermal cycling and testing under high temperature reverse bias conditions in order to address their reliability for use in space missions. Result of the experimental work are presented and discussed.

Patterson, Richard L.; Boomer, Kristen T.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

2014-01-01

384

Growth of gallium arsenide using ion cluster beam technology  

NASA Astrophysics Data System (ADS)

The growth of single crystal gallium arsenide (GaAs) epitaxial films on high resistivity GaAs substrates has been demonstrated. Films were grown at substrate temperatures from 600C down to 400C with thicknesses from 3000A to 5 micron. Growth rates were typically 150A/minute at all growth temperatures with thickness uniformity of + or - 5% over the sample (typical sample size 0.7in. X 0.7in.). The thickness was measured by a standard cleave and stain method. Single crystal behavior was shown using X-ray diffraction and SEM channeling patterns. Auger analysis was done on the films and showed characteristics comparable to those of the substrate. Hall data taken on the samples found the samples to be n-type, but with very low mobility. The low mobility is the result of defects grown into the structure because of high energy ions impinging on the surface. The energy of the ions was in the range of 100 to 1000 ev because of the small cluster size. The cluster had sizes of 10-50 atoms instead of the desired 500-2000 atoms/cluster. This smaller cluster is likely due to non-uniform heating of the crucibles by the e-beam filament. In addition, the diameter/length of the opening in the nozzle was 1:1. Recent work suggests a 1:10 ratio will allow more interactions and thus enhance the possibility of forming larger clusters. With larger clusters, lower energy per ion will be possible and the native defects will be reduced.

Adams, Robert L.

1986-08-01

385

Gallium-cladding compatibility testing plan: Phase 3 -- Test plan for centrally heated surrogate rodlet test. Revision 2  

SciTech Connect

The Fissile Materials Disposition Program (FMDP) is investigating the use of weapons grade plutonium in mixed oxide (MOX) fuel for light-water reactors (LWR). Commercial MOX fuel has been successfully used in overseas reactors for many years; however, weapons derived fuel may differ from the previous commercial fuels because of small amounts of gallium impurities. A concern presently exists that the gallium may migrate out of the fuel, react with and weaken the clad, and thereby promote loss of fuel pin integrity. Phases 1 and 2 of the gallium task are presently underway to investigate the types of reactions that occur between gallium and clad materials. This is a Level-2 document as defined in the Fissile Materials Disposition Program Light-Water Reactor Mixed-Oxide Fuel Irradiation Test Project Plan. This Plan summarizes the projected Phase 3 Gallium-Cladding compatibility heating test and the follow-on post test examination (PTE). This work will be performed using centrally-heated surrogate pellets, to avoid unnecessary complexities and costs associated with working with plutonium and an irradiation environment. Two sets of rodlets containing pellets prepared by two different methods will be heated. Both sets will have an initial bulk gallium content of approximately 10 ppm. The major emphasis of the PTE task will be to examine the material interactions, particularly indications of gallium transport from the pellets to the clad.

Morris, R.N.; Baldwin, C.A.; Wilson, D.F.

1998-07-01

386

Austenitic stainless steel alloy  

Microsoft Academic Search

This patent describes a stainless steel alloy composition for service exposed to irradiation, having resistance to irradiation promoted stress corrosion cracking and reduced long term irradiation induced radioactivity. The alloy consisting of a low carbon content austenitic stainless steel alloy composition comprising about 18 to 20 percent weight of chromium, about 9 to 11 percent weight of nickel, about 1.5

D. J. Coates; G. M. Gordon; A. J. Jacobs; D. W. Sandusky

1989-01-01

387

Alloys for aerospace  

Microsoft Academic Search

Aerospace industries require special allows with many properties tailored to meet specific needs. Prerequisites include clean melting techniques to maintain low impurity levels, tight control of alloy chemistry, and the analytical capability to characterize the product. Teledyne Wah Chang (TWC) produces specially refractory metals, including zirconium, hafnium, titanium, niobium and vanadium, which are essential components of many aerospace alloys. Alloys

S. Tuominen; C. Wojcik

1995-01-01

388

BRIEF COMMUNICATIONS: Mode locking in a neodymium laser with a gadolinium scandium gallium garnet switch  

NASA Astrophysics Data System (ADS)

A study was made of mode locking in a neodymium laser with a passive gadolinium scandium gallium garnet (GSGG) passive switch. When the transmission coefficient of GSGG was T= 20% and the length of the crystal was 1 cm, ultrashort pulses of minimum duration 80 psec and of energy of 0.5 mJ per pulse were generated.

Demchuk, M. I.; Zharikov, Evgeny V.; Zabaznov, A. M.; Manichev, I. A.; Mikha?lov, V. P.; Prokhorov, A. M.; Shkadarevich, A. P.; Chernyakovski?, A. F.; Shcherbakov, Ivan A.; Yumashev, K. V.

1987-02-01

389

Cationic ring-opening polymerization of tetrahydrofuran with boron, aluminium, and gallium tristriflate  

SciTech Connect

Boron, aluminum, and gallium tristriflate are new effective catalysts for the polymerization of tetrahydrofuran (THF). High-molecular-weight polytetrahydrofuran (PTHF) obtained in excellent yield in the bulk polymerization of THF at ambient temperature with all three catalysts. The PTHF samples are characterized and some of their thermodynamic and mechanical properties are investigated and discussed in this paper.

Olah, G.A.; Farooq, O.; Li, C.H.; Farnia, M.A.M.; Aklonis, A. (University of Southern California, Los Angeles, CA (United States). Dept. of Chemistry)

1992-07-25

390

Study of gallium phosphate and langasite crystals and resonators by X-ray topography  

Microsoft Academic Search

The gallium phosphate (GaPO4) is, as berlinite, a close crystallographic analogue of quartz with the advantage that it has no ?-? phase transition. It was shown that this material has very attractive properties for the applications to piezoelectric devices, due to its large coupling coefficients and to the existence of compensated cuts. Furthermore, it can be used up to extremely

B. Capelle; A. Zarka; J. Detaint; J. Schwartzel; A. Ibanez; E. Philippot; J. P. Denis

1994-01-01

391

Gallium arsenide integrated optical devices for high-speed diagnostic systems  

SciTech Connect

The design, fabrication, and evaluation of waveguide electro-optic modulators in gallium arsenide for application to high-speed diagnostic systems are discussed specifically. This paper is focused on high bandwidth, single event analog modulation, and radiation susceptibility of these devices.

McWright, G.; Lowry, M.; Takeuchi, E.; Murphy, G.; Tindall, W.; Koo, J.; Roeske, F.

1987-01-01

392

Spectral Data for Gallium: Ga I through Ga XXXI T. Shiraia...  

E-print Network

Spectral Data for Gallium: Ga I through Ga XXXI T. Shiraia... Naka Fusion Research Establishment for spectra Ga I through Ga VII, Ga XIII through Ga XXVI, and Ga XXX. For Li-like Ga XXIX through H-like Ga XXXI, theoretical data on energy levels and line wavelengths are compiled. For Ga I, Ga II, and Ga III

Magee, Joseph W.

393

Skylab experiment performance evaluation manual. Appendix J: Experiment M555 gallium arsenide single crystal growth (MSFC)  

NASA Technical Reports Server (NTRS)

Analyses for Experiment M555, Gallium Arsenide Single Crystal Growth (MSFC), to be used for evaluating the performance of the Skylab corollary experiments under preflight, inflight, and post-flight conditions are presented. Experiment contingency plan workaround procedure and malfunction analyses are presented in order to assist in making the experiment operationally successful.

Byers, M. S.

1973-01-01

394

On-orbit annealing of gallium arsenide solar cell arrays. Master's thesis  

SciTech Connect

A complete experimental package is developed for the acquisition of current-voltage curves and the annealing of gallium arsenide solar cells and arrays of cells. This package is designed to be placed aboard a wide variety of satellite buses and to operate with little interface to the satellite system.

Sommers, R.S.

1989-06-01

395

Barrier-height measurement for a gallium arsenide metal-semi-insulator interface  

SciTech Connect

The I-V characteristics of structures from semi-insulating gallium arsenide with different contacts are analyzed. The Schottky barrier height was measured using two procedures; its values obtained for vanadium-based contacts amount to 0.81 {+-} 0.02 V.

Ayzenshtat, G. I., E-mail: ayzen@mail.tomsknet.ru; Lelekov, M. A.; Tolbanov, O. P. [Tomsk State University (Russian Federation)

2007-11-15

396

Infected cyst localization with gallium SPECT imaging in polycystic kidney disease  

SciTech Connect

This case report describes a 43-year-old woman with polycystic renal disease and cyst infection. Infected cysts of the left kidney were successfully localized with Ga-67 citrate SPECT imaging and CT. Other imaging, including planar gallium imaging, was helpful diagnostically, but could not determine the exact location of infection within the kidney.

Amesur, P.; Castronuovo, J.J.; Chandramouly, B.

1988-01-01

397

Electrical Conductivity of Solutions of Aluminium (III), Gallium (III) and Indium (III) Iodides in Alkyl Iodides  

Microsoft Academic Search

SEVERAL investigations have been devoted to the electrical conductivity of aluminium halides in alkyl halide solutions1-5. The conductance of these solutions has been attributed to the formation of some complexes or addition compounds composed of both interacting molecules. No investigations on analogous systems with gallium and indium halides have hitherto been performed. In order to gain more information of the

A. Halpern; A. POLACZEK

1963-01-01

398

Self-focusing in Terbium Gallium Garnet using Z-scan  

Microsoft Academic Search

When illuminated near its resonance with an Ar ion laser beam (?=488 nm), laser induced thermal self-focusing is observed in Terbium Gallium Garnet. The crystal exhibits a strong intensity dependent refractive index change ?n. The Z-scan technique is used to study the beam waist change due to ?n. The refractive index is found to be well described by a quadratic

X. Chen; B. Lavorel; T. Dreier; N. Genetier; H. Misserey; X. Michaut

1998-01-01

399

Terbium gallium garnet for high average power Faraday isolators: modern aspects of growing and characterization  

Microsoft Academic Search

The growth and characterization of terbium gallium garnet (TGG) for high average Faraday isolators is reported. The main technique of TGG single crystals growing is Czochralski method. Key physical parameters of the grown crystals are measured: thermal conductivity, heat capacity, thermal expansion coefficient, refractive index thermal dependence, optical damage threshold and spectral function of Verdet constant.

I. Ivanov; A. Bulkanov; E. Khazanov; I. Mukhin; O. Palashov; V. Tsvetkov; P. Popov

2009-01-01

400

FORMATION OF MESOPOROUS GALLIUM ARSENIDE FOR LIFT-OFF PROCESSES BY ELECTROCHEMICAL ETCHING  

E-print Network

FORMATION OF MESOPOROUS GALLIUM ARSENIDE FOR LIFT-OFF PROCESSES BY ELECTROCHEMICAL ETCHING Enrique form reproducibly. Porous layers thicker than 7 µm automatically lift-off from the substrate. We lift-off technique (ELO) [4]-[6] permits the separation of an epitaxially grown III-V device from a Ga

401

Adaptive behavior of a redox-active gallium carbenoid in complexes with molybdenum.  

PubMed

A gallium(I) carbenoid derived from redox-active diimine 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) in complexes with molybdenum may serve either as a neutral [(dpp-bian)Ga:] or an anionic [(dpp-bian)Ga:](-) two-electron donor depending on the electronic state of the transition metal. PMID:25050806

Fedushkin, Igor L; Sokolov, Vladimir G; Piskunov, Alexander V; Makarov, Valentine M; Baranov, Eugeny V; Abakumov, Gleb A

2014-09-11

402

NMR microspectroscopy using 100 \\/spl mu\\/m planar RF coils fabricated on gallium arsenide substrates  

Microsoft Academic Search

A family of planar gold RF microcoils were fabricated using microlithography on a gallium arsenide substrate. The microcoils were used in 1H nuclear magnetic resonance (PIMR) spectroscopy experiments at 300 MHz (7.05 T). These new microcoils are a key component in the design of integrated MR coils and amplifiers for NMR microspectroscopy.

T. L. Peck; R. L. Magin; J. Kruse; M. Feng

1994-01-01

403

Optical, electrical, and solar energy-conversion properties of gallium arsenide nanowire-array  

E-print Network

Optical, electrical, and solar energy-conversion properties of gallium arsenide nanowire-array Dapkus,*b Nathan S. Lewis*ad and Chongwu Zhoub Periodic arrays of n-GaAs nanowires have been grown characteristics of the nanowire-arrays were investigated experimentally and theoretically

Zhou, Chongwu

404

Gallium citrate Ga 67 accumulation in pulmonary lesions after chemotherapy (MOPP)  

SciTech Connect

We have described a patient with Hodgkin's disease who had fever and pulmonary infiltrates after treatment with mantle x-ray therapy and two courses of MOPP. Gallium affinity of the lung lesions proved at biopsy not to be due to Hodgkin's disease, but probably to chemotherapy-induced pulmonary toxicity.

Wells, J.D.; Huskison, W.T.; Davenport, O.L.

1986-10-01

405

Polyaniline\\/gallium doped ZnO heterostructure device via plasma enhanced polymerization technique: Preparation, characterization and electrical properties  

Microsoft Academic Search

The ZnO and gallium-doped ZnO nanoparticles (NPs) were synthesized by simple chemical method and used for the fabrication\\u000a of p-polyaniline\\/n-ZnO heterostructures devices in which polyaniline was deposited by plasma-enhanced polymerization. The\\u000a increment in the crystallite sizes of gallium doped ZnO nanoparticles from ~21.85 nm to ~32.39 nm indicated the incorporation\\u000a of gallium ion into the ZnO nanoparticles. The surface and structural studies

Sadia Ameen; M. Shaheer Akhtar; Young Soon Kim; O-Bong Yang; Hyung-Shik Shin

2011-01-01

406

Properties of plutonium and its alloys for use as fast reactor fuels  

NASA Astrophysics Data System (ADS)

Early interest in metallic plutonium fuels for fast reactors led to much research on plutonium alloy systems including binary solid solutions with the addition of aluminum, gallium, or zirconium and low melting eutectic alloys with iron and nickel or cobalt. There was also interest in ternaries of these elements with plutonium and cerium. The solid solution and eutectic alloys have most unusual properties, including negative thermal expansion in some solid-solution alloys and the highest viscosity known for liquid metals in the Pu-Fe system. Although metallic fuels have many potential advantages over ceramic fuels, the early attempts were unsuccessful because these fuels suffered from high swelling rates during burn up and high smearing densities. The liquid metal fuels experienced excessive corrosion. Subsequent work on higher melting U-Pu-Zr metallic fuels was much more promising. In light of the recent rebirth of interest in fast reactors, we review some of the key properties of the early fuels and discuss the challenges presented by the ternary alloys.

Hecker, Siegfried S.; Stan, Marius

2008-12-01

407

Preparation and characterization of thin, atomically clean gallium nitride(0001) and aluminum nitride(0001) films and the deposition of thick gallium nitride films via iodine vapor phase growth  

NASA Astrophysics Data System (ADS)

The research conducted for this dissertation involved two tasks important to the achievement of (1) improved interfaces in future III-nitride devices and (2) GaN substrates for homoepitaxial growth of III-nitride films and material device structures. The initial phase of this work determined an effective technique for the removal of oxygen and hydrocarbon contamination from GaN(0001) and AlN(0001) surfaces. Through the combined use of several surface evaluation techniques, a chemical vapor treatment with ammonia in a UHV environment was developed. The optimal conditions for GaN were 860°C for 15 minutes at 10-4 Torr, and for AlN were 1120°C for 30 minutes at 10-4 Torr. The surface microstructures of each material were undamaged, and important electrical and optical properties of the treated surfaces were determined. The technique was adapted to clean the surface of a GaN thin film substrate prior to homoepitaxial growth via metal-organic vapor phase epitaxy (MOVPE). Introducing ammonia into the gas mixture during heating resulted in reduction of the contamination at the interface between the substrate and a subsequently grown GaN film. Rapid growth of thick GaN films was achieved via the reaction between gallium iodide species and ammonia on various substrates. The iodine and gallium transport rates in the custom reactor were lower than expected from thermodynamic equilibrium calculations due to high gas flow rate relative to the volume of the iodine and gallium sources. The gallium transport remained a function of the iodine flow rate, and the growth rate was a function of the amount of gallium delivered to the seed. The maximum growth rate achieved was 155 mum/hr for 1 hour. Cracking was observed in all films grown via IVPG, even when the substrate was changed from sapphire to SIC. Use of a gold layer as an in-situ mask did not reduce the cracking when the GaN was deposited over the gold layer.

Mecouch, William J.

408

Composition of Earth's core from gallium metal-silicate partitioning experiments  

NASA Astrophysics Data System (ADS)

Earth's Core formation has left an imprint in the composition of the mantle, by depleting and fractionating the siderophile trace elements. However, some siderophile element concentrations in Earth's mantle cannot be explained by simple metal-silicate partitioning during the accretion and core formation. Gallium, for instance, is a moderately siderophile element which is not depleted in Earth's mantle relative to the lithophile volatility trend, and therefore shows the characteristics of a lithophile element. This peculiarity cannot be explained by any accretion/core formation scenario in the literature. This is due to the fact that all studies of the partitioning of gallium between metal and silicate (with the effects of pressure, temperature, silicate composition and redox) have shown it to remain siderophile. We will present our study of the effect of metal composition on the partitioning of gallium. Light elements (silicon and sulphur in our study) in the core should affect the activity coefficient of gallium in the metal, and hence its partitioning between metal and silicate. We performed a series of isobaric and isothermal experiments (2 GPa, 1800°C) in an end-loaded piston cylinder press, and varied the Si and S content of the metal phase. We observed that the addition of Si and S makes gallium more lithophile, and this illustrates once more that the light elements present in the core play a fundamental role in metal-silicate equilibrium and in explaining the abundance of trace elements in Earth's mantle. We will also present models core formation that are compatible with our measurements.

Blanchard, I.; Badro, J.; Siebert, J.

2012-12-01

409

Creep Resistant Zinc Alloy  

SciTech Connect

This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

Frank E. Goodwin

2002-12-31

410

Creating and imaging surface acoustic waves on gallium arsenide  

NASA Astrophysics Data System (ADS)

The versatility of surface acoustic wave (SAW) devices stems from the accessibility of the propagation path to modification and detection. This has led to the integration of SAWs in a variety of novel fields, including quantum information processing. The development of technologically competitive devices requires the use of gigahertz frequency SAWs. This thesis develops fabrication processes for high frequency interdigital transducers on gallium arsenide. Optically lithography was used to create linear and stepped transducers, with a minimum feature size of 2 mum, that were driven at their fifth harmonic. The highest frequency achieved was 1435 MHz, but the power absorbed was less than 3% and insertion losses were greater than --80 dB. Further improvements in the design and fabrication are required if optically fabricated transducers are to be an alternative to transducers with narrower finger widths. Electron-beam lithography techniques were developed and used to create transducers with finger widths of 500 and 400 nm, with fundamental resonance frequencies of 1387 and 1744 MHz, respectively. The power absorbed was 3 to 6% with insertion losses greater than --45 dB. The performance characteristics can be improved by the removal of residual resist on the surface of the transducer. An indispensable tool for the characterization of one-port transducers is an all optical probe to measure the displacement field of a SAW. This work details the design and construction of a scanning Sagnac interferometer that is capable of measuring the outward displacement of a surface. The spatial resolution of the interferometer was 2:4+/-0:2 mum and the displacement sensitivity was determined to be 4+/-1 pm. The instrument was used to map the SAW displacement field from a 358MHz transducer, with results showing the resonant cavity behaviour of the fingers due to Bragg reflections. It also allowed for the direct detection of the SAW amplitude as a function of the driving frequency of the transducer. The results showed good agreement with the related S21 scattering parameter. Lastly, the interferometer was used to image the attenuated propagation of SAWs through a phononic crystal. Results showed good agreement with theoretical simulations.

Mathew, Reuble

411

Recovery of uranium alloy  

SciTech Connect

A method is described of recovery of uranium alloy from a mixture of uranium alloy with magnesium fluoride comprising: (a) pretreating uranium fluoride with magnesium at 400/sup 0/-1250/sup 0/C. to form a pretreated mixture of uranium and magnesium fluoride, (b) introducing the pretreated mixture into a molten-salt bath floating on a molten-uranium-alloy trap, (c) allowing the bath to transfer heat to the pretreated mixture to cause the magnesium fluoride to dissolve into the molten-salt bath and the uranium alloy to be molten, (d) allowing molten uranium alloy from the pretreated mixture in the bath to separate from the bath into the trap, (e) discharging separated molten-uranium alloy from the trap, and (f) discharging non-alloy components of the pretreated mixture along with excess molten salt from the bath.

Elliott, G.R.B.

1987-01-13

412

IEEE Spectrum: Thin-Film Trick Makes Gallium Arsenide Devices Cheap http://spectrum.ieee.org/semiconductors/materials/thinfilm-trick-makes-gallium-arsenide-devices-cheap[5/22/2010 1:39:13 PM  

E-print Network

.16.2010 Kokoro's I-Fairy Robot Conducts Wedding in Japan The groom is a robotics researcher. The bride is that compound semiconductors are much more expensive than silicon. A 6-inch wafer of gallium arsenide costs

Rogers, John A.

413

CD2Alloy: Class Diagrams Analysis Using Alloy Revisited  

E-print Network

CD2Alloy: Class Diagrams Analysis Using Alloy Revisited Shahar Maoz , Jan Oliver Ringert present CD2Alloy, a novel, powerful translation of UML class diagrams (CDs) to Alloy. Unlike existingAlloy uses a deeper embedding strategy. Rather than mapping each CD construct to a semantically

Maoz, Shahar

414

Research on mechanically alloyed aluminum alloy products for aerospace applications  

Microsoft Academic Search

Mechanically alloyed (MA) aluminum alloys represent an advanced aluminum powder metallurgy technology. Chemically homogeneous alloy powders containing a fine distribution of oxide and carbide dispersoids are manufactured by mechanical alloying, an INCO propriety process involving high energy milling of elemental powders. This process allows a desirable chemistry\\/microstructure\\/property combination to be engineered into the alloy. Consolidation by canless vacuum hot pressing

R. D. Schelleng; P. S. Gilman; A. D. Jatkar; S. J. Donachie

2008-01-01

415

Weldability of High Alloys  

SciTech Connect

The purpose of this study was to investigate the effect of silicon and iron on the weldability of HAYNES HR-160{reg_sign} alloy. HR-I60 alloy is a solid solution strengthened Ni-Co-Cr-Si alloy. The alloy is designed to resist corrosion in sulfidizing and other aggressive high temperature environments. Silicon is added ({approx}2.75%) to promote the formation of a protective oxide scale in environments with low oxygen activity. HR-160 alloy has found applications in waste incinerators, calciners, pulp and paper recovery boilers, coal gasification systems, and fluidized bed combustion systems. HR-160 alloy has been successfully used in a wide range of welded applications. However, the alloy can be susceptible to solidification cracking under conditions of severe restraint. A previous study by DuPont, et al. [1] showed that silicon promoted solidification cracking in the commercial alloy. In earlier work conducted at Haynes, and also from published work by DuPont et al., it was recognized that silicon segregates to the terminal liquid, creating low melting point liquid films on solidification grain boundaries. Solidification cracking has been encountered when using the alloy as a weld overlay on steel, and when joining HR-160 plate in a thickness greater than19 millimeters (0.75 inches) with matching filler metal. The effect of silicon on the weldability of HR-160 alloy has been well documented, but the effect of iron is not well understood. Prior experience at Haynes has indicated that iron may be detrimental to the solidification cracking resistance of the alloy. Iron does not segregate to the terminal solidification product in nickel-base alloys, as does silicon [2], but iron may have an indirect or interactive influence on weldability. A set of alloys covering a range of silicon and iron contents was prepared and characterized to better understand the welding metallurgy of HR-160 alloy.

Maroef, I

2003-01-22

416

Alloy 10: A 1300F Disk Alloy  

NASA Technical Reports Server (NTRS)

Gas turbine engines for future subsonic transports will probably have higher pressure ratios which will require nickel-base superalloy disks with 13000 to 1400 F temperature capability. Several advanced disk alloys are being developed to fill this need. One of these, Allied Signal's Alloy 10, is a promising candidate for gas turbine engines to be used on smaller, regional aircraft. For this application, compressor/turbine disks must withstand temperatures of 1300 F for several hundred hours over the life of the engine. In this paper, three key properties of Alloy 10--tensile, 0.2% creep, and fatigue crack growth--will be assessed at 1300 F.

Gayda, John

2000-01-01

417

The intermetallic phases of gallium and alkali metals. Interpretation of the structures according to Wade's electron-counting methods  

NASA Astrophysics Data System (ADS)

This is a survey of the preparation and structural properties of the intermetallic phases of gallium and alkali metals. Unlike the already known phases of gallium with lithium or sodium, the structures of the recently discovered phases Li 3Ga 14, Na 22Ga 39, KGa 3, K 3Ga 13, RbGa 3, RbGa 7, and CsGa 7 are characterized by stackings of coordinated gallium polyhedra such as icosahedra, octadecahedra, dodecahedra, and undecahedra. In these phases the alkali metals stabilize the gallium framework by giving their valence electrons. On this basis, the structures are interpreted according to Wade's electron-counting procedure, bringing the Zintl phases to a more general concept and enhancing the interest on the transition forms between metallic and ionic bonding.

Belin, Claude; Ling, Rong Guo

1983-06-01

418

Separation and recovery of gallium and indium from simulated zinc refinery residue by liquid-liquid extraction  

Microsoft Academic Search

The separation and recovery of gallium and indium from zinc refinery residue, using liquid-liquid extraction, has been investigated. The major components with the exception of zinc can be removed by extraction with tri-n-butyl phosphate at low aqueous acidity, and gallium and indium can be separated from the remaining major component, zinc, by extraction with bis(2-ethylhexyl)phosphoric acid (D2EHPA) using the correct

Syouhei Nishihama; Takayuki Hirai; Isao Komasawa

1999-01-01

419

Ion-beam-assisted molecular-beam epitaxy: a method to deposit gallium nitride films with high crystalline quality  

Microsoft Academic Search

Hexagonal gallium nitride has been deposited on 6H-SiC by low-energy-ion-beam-assisted molecular-beam epitaxy. X-Ray diffraction measurements indicate the high crystalline quality of the thin films. Cross-section transmission electron microscopy images prove that a two-dimensional growth mode is obtained with this technique in contrast to the columnar growth of gallium nitride, as it is known from other methods. Comparing the ion energy

S. Sienz; J. W. Gerlach; T. Höche; A. Sidorenko; B. Rauschenbach

2004-01-01

420

Gallium(III) Trifluormethanesulfonate: A Water-Tolerant, Reusable Lewis Acid Catalyst for Friedel-Crafts Reactions  

Microsoft Academic Search

The application of gallium(III) trifluoromethanesulfonate (triflate, OTf) in Friedel-Crafts alkylation and acylation reactions is described. Gallium triflate was found to be an excellent catalyst for the adamantylation of toluene with 1-bromoadamantane, where its activity was compared to that of well-known rare earth metal triflates. As Ga(OTf)3 does not decompose in the presence of water the isopropylation of aromatics can be

G. K. Surya Prakash; Ping Yan; Béla Török; Imre Bucsi; Mutsuo Tanaka; George A. Olah

2003-01-01

421

The 13.9 GHz short pulse radar noise figure measurements utilizing silicon and gallium-arsenide mixer diodes  

NASA Technical Reports Server (NTRS)

An analysis was made on two commercially available silicon and gallium arsenide Schottky barrier diodes. These diodes were selected because of their particularly low noise figure in the frequency range of interest. The specified noise figure for the silicon and gallium arsenide diodes were 6.3 db and 5.3 db respectively when functioning as mixers in the 13.6 GHz region with optimum local oscillator drive.

Dombrowski, M.

1977-01-01

422

Effect of Electron Donors on the Isotopic Exchange between Aluminium (III), Gallium (III) and Indium (III) Iodides and Alkyl Iodides  

Microsoft Academic Search

VERY few investigations have been devoted to the isotopic exchange reactions of halogens in AlX3-RX solutions1, where X is a halogen atom and R is an alkyl radical. No work on analogous systems with gallium and indium halides has hitherto been published. In the work recorded here, the isotopic exchange reactions of iodine between aluminium, gallium and indium triiodides and

A. Polaczek; A. Halpern

1963-01-01

423

X-ray study of the oxidation of liquid-gallium surfaces M. J. Regan,* H. Tostmann, and P. S. Pershan  

E-print Network

X-ray study of the oxidation of liquid-gallium surfaces M. J. Regan,* H. Tostmann, and P. S-Gan 52100, Israel Received 21 November 1996 The oxidation of liquid-gallium surfaces has been investigated on the order of 180 L of oxygen where 1 L 10 6 Torr s, a gallium oxide film with a well-defined thickness of 5

Grigoriev, Alexei

424

Catalyst Alloys Processing  

NASA Astrophysics Data System (ADS)

Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

Tan, Xincai

2014-10-01

425

Measurement of Impact Ionization Coefficients in Gallium Nitride  

NASA Astrophysics Data System (ADS)

GaN has been recognized as a potential semiconductor for high temperature, high frequency and high power applications. Due to its wide bandgap, GaN exhibits high critical electric fields, which are suitable to sustain high breakdown voltages in power electronic devices. In order to obtain a good understanding of the breakdown characteristics of a power device, it is important to know the impact ionization coefficients of electrons and holes as a function of the electric field in the semiconductor. In this work, electron and hole impact ionization coefficients have been accurately measured in both GaN epitaxial layers grown on bulk GaN substrates and GaN epitaxial layers grown on Sapphire substrates using the pulsed electron beam induced current technique. Using Chynoweth's equation (alpha = a e-b/E), measurements for GaN epitaxial layer grown on bulk GaN substrates gave an aN value of 1.5x105 cm-1 and a bN value of 1.413x107 V/cm for the impact ionization coefficient of electrons in GaN at room temperature. For the impact ionization coefficients of holes in GaN, the values of aP and bP were found to be 6.4x105 cm-1 and 1.454x107 V/cm, respectively. An analytical solution of the form alpha = mEn for the variation of the impact ionization coefficients as a function of the electric field was derived, which is useful for analytical calculation of the breakdown voltages in GaN. For Chynoweth's equation (alpha = a e-b/E), measurements for GaN epitaxial layers grown on Sapphire substrates gave an aN value of 9.17x105 cm-1 and a bN value of 1.722x107 V/cm for the impact ionization coefficient for electrons at room temperature. For the impact ionization coefficients for holes at room temperature, the values of aP and bP were found to be 8.7x105 cm-1 and 1.464x107 V/cm, respectively. The values for both coefficients are larger than those measured for GaN grown on GaN substrates. The temperature dependence of the electron and hole impact ionization coefficients as a function of the electric field has been accurately measured for both GaN epitaxial layers grown on bulk GaN substrates and GaN epitaxial layers grown on Sapphire substrates. The impact ionization coefficients for both electrons and holes are observed to decrease with increasing temperature. This is consistent with the measured increase in the breakdown voltage with temperature for high voltage Schottky barrier diodes. This is an important observation demonstrating that stable power devices can be fabricated from Gallium Nitride. Electron Beam Induced Current (EBIC) technique was employed in order to understand the role of defects on the breakdown characteristics of GaN. The impact ionization coefficients for electrons and holes measured at the defective site were found to be higher than those measured at a non-defective site. These results indicate that the breakdown voltage of GaN devices can be reduced due to the presence of defects.

Ozbek, Ayse Merve

426

Low activation ferritic alloys  

DOEpatents

Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

Gelles, David S. (West Richland, WA); Ghoniem, Nasr M. (Granada Hills, CA); Powell, Roger W. (Pasco, WA)

1986-01-01

427

Low activation ferritic alloys  

DOEpatents

Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

1985-02-07

428

Translating Z to Alloy  

Microsoft Academic Search

\\u000a Few tools are available to help with the difficult task of validating that a Z specification captures its intended meaning.\\u000a One tool that has been proven to be useful for validating specifications is the Alloy Analyzer, an interactive tool for checking\\u000a and visualising Alloy models. However, Z specifications need to be translated to Alloy notation to make use of the

Petra Malik; Lindsay Groves; Clare Lenihan

2010-01-01

429

Amorphous metal alloy  

DOEpatents

Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

Wang, R.; Merz, M.D.

1980-04-09

430

Advanced aerospace Al alloys  

Microsoft Academic Search

SiC particulate or whisker-reinforced aluminum alloys are very attractive for applications requiring high stiffness coupled with a comparatively light weight. The dispersion strengthened Al alloys produced through the rapid solidification processing\\/powder metallurgy route demonstrate superior elevated temperature strength and microstructural stability, extending the useful service temperature of Al alloys to 350 C. However, low ductility and poor fracture toughness levels

K. S. Ravichandran; E. S. Dwarakadasa

1987-01-01

431

Transport properties of gallium nitride nanowire metal-oxide-semiconductor transistor  

NASA Astrophysics Data System (ADS)

We investigated the transport properties of [112¯0]-gallium nitride (GaN)/gallium oxide (Ga2O3) single nanowire metal-oxide-semiconductor field-effect-transistor grown on (0001) sapphire substrates. With 0.1 ?m gate-length and 60 nm wire-size, the device exhibits maximum transconductance of 85 ?S, saturation current of 105 ?A, and unity current gain bandwidth ft at 95 GHz. From a three-dimensional (3D) diffusion-and-drift model analysis, polarization-induced negative space charge of -3 × 1012 cm-2 at the back interface of GaN/sapphire, positive space charge of 7 × 1012 cm-2 at the inclined semi-polar {11¯01¯} GaN/Ga2O3 interfaces with screening by two-dimensional electron gas to keep charge neutrality were found responsible for the high-speed transport characteristics.

Yu, J.-W.; Li, C.-K.; Chen, C.-Y.; Wu, Y.-R.; Chou, L.-J.; Peng, L.-H.

2011-10-01

432

Gallium nitride thin films deposited by radio-frequency magnetron sputtering  

SciTech Connect

Effects of self-induced negative bias in radio-frequency (rf) sputtering on the structure of the deposited film are discussed on the basis of the measured characteristics of the gallium nitride (GaN) films. A powdered GaN target was sputtered by either argon (Ar) or nitrogen (N{sub 2}) gas to investigate the effects of the sputtering. When sputtering with Ar gas, the resputtering due to the ion bombardments produces a film deficient in nitrogen with poor crystallinity. The ion bombardment eventually destroys the crystal structure producing a black amorphous film caused by gallium atoms forming clusters. Alternatively, when sputtering with N{sub 2} gas, the activated nitrogen atmosphere enhances nitrogen incorporation and prevents the destruction of the crystal structure, making the film stoichiometric. To obtain high crystallinity, the effect of the self-induced negative bias should be minimized by decreasing the rf power and increasing the total pressure.

Maruyama, Toshiro; Miyake, Hidetomo [Department of Chemical Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8510 (Japan)

2006-07-15

433

The fabrication of silicon nanostructures by local gallium implantation and cryogenic deep reactive ion etching.  

PubMed

We show that gallium-ion-implanted silicon serves as an etch mask for fabrication of high aspect ratio nanostructures by cryogenic plasma etching (deep reactive ion etching). The speed of focused ion beam (FIB) patterning is greatly enhanced by the fact that only a thin approx. 30 nm surface layer needs to be modified to create a mask for the etching step. Etch selectivity between gallium-doped and undoped material is at least 1000:1, greatly decreasing the mask erosion problems. The resolution of the combined FIB-DRIE process is 20 lines microm(-1) with the smallest masked feature size of 40 nm. The maximum achieved aspect ratio is 15:1 (e.g. 600 nm high pillars 40 nm in diameter). PMID:19417383

Chekurov, N; Grigoras, K; Peltonen, A; Franssila, S; Tittonen, I

2009-02-11

434

Thermodynamic property evaluation and magnetic refrigeration cycle analysis for gadolinium gallium garnet  

SciTech Connect

Based on relevant material property data and previous model formulations, a magnetothermodynamic property map for gadolinium gallium garnet (Gd{sub 3}Ga{sub 5}O{sub 12}) was adapted for refrigeration cycle analysis in the temperature range 4-40 K and the magnetic field range 0-6 T. Employing methods similar to those previously developed for other materials and temperature ranges, assessments of limitations and relative performance were made for Carnot, ideal regenerative, and pseudo-constant field regenerative cycles. It was found that although Carnot cycle limitations on available temperature lift for gadolinium gallium garnet are not as severe as the limitations for materials previously examined, considerable improvement in cooling capacity and temperature lift combinations can be achieved by using regenerative cycles if serious loss mechanisms are avoided.

Murphy, R.W.

1994-12-01

435

Direct growth of graphene on gallium nitride by using chemical vapor deposition without extra catalyst  

NASA Astrophysics Data System (ADS)

Graphene on gallium nitride (GaN) will be quite useful when the graphene is used as transparent electrodes to improve the performance of gallium nitride devices. In this work, we report the direct synthesis of graphene on GaN without an extra catalyst by chemical vapor deposition. Raman spectra indicate that the graphene films are uniform and about 5-6 layers in thickness. Meanwhile, the effects of growth temperatures on the growth of graphene films are systematically studied, of which 950 °C is found to be the optimum growth temperature. The sheet resistance of the grown graphene is 41.1 ?/square, which is close to the lowest sheet resistance of transferred graphene reported. The mechanism of graphene growth on GaN is proposed and discussed in detail. XRD spectra and photoluminescence spectra indicate that the quality of GaN epi-layers will not be affected after the growth of graphene.

Zhao, Yun; Wang, Gang; Yang, Huai-Chao; An, Tie-Lei; Chen, Min-Jiang; Yu, Fang; Tao, Li; Yang, Jian-Kun; Wei, Tong-Bo; Duan, Rui-Fei; Sun, Lian-Feng

2014-09-01

436

Fast neutron scattering on Gallium target at 14.8 MeV  

E-print Network

Benchmarking of evaluated nuclear data libraries was performed for $\\sim 14.8$ MeV neutrons on Gallium targets. The experiments were performed at China Institute of Atomic Energy(CIAE). Solid samples of natural Gallium (3.2 cm and 6.4 cm thick) were bombarded by $\\sim 14.8$ MeV neutrons and leakage neutron energy spectra were measured at 60$^{\\circ}$ and 120$^{\\circ}$. The measured spectra are rather well reproduced by MCNP-4C simulations with the CENDL-3.1, ENDF/B-VII and JENDL-4.0 evaluated nuclear data libraries, except for the inelastic contributions around $E_{n} = 10-13$ MeV. All three libraries significantly underestimate the inelastic contributions. The inelastic contributions are further studied, using the Talys simulation code and the experimental spectra are reproduced reasonably well in the whole energy range by the Talys calculation, including the inelastic contributions.

Han, R; Chen, Z; Nie, Y; Liu, X; Zhang, S; Ren, P; Jia, B; Tian, G; Luo, F; Lin, W; Liu, J; Shi, F; Huang, M; Ruan, X; Ren, J; Zhou, Z; Huang, H; Bao, J; Zhang, K; Hu, B

2014-01-01

437

Fast neutron scattering on Gallium target at 14.8 MeV  

E-print Network

Benchmarking of evaluated nuclear data libraries was performed for $\\sim 14.8$ MeV neutrons on Gallium targets. The experiments were performed at China Institute of Atomic Energy(CIAE). Solid samples of natural Gallium (3.2 cm and 6.4 cm thick) were bombarded by $\\sim 14.8$ MeV neutrons and leakage neutron energy spectra were measured at 60$^{\\circ}$ and 120$^{\\circ}$. The measured spectra are rather well reproduced by MCNP-4C simulations with the CENDL-3.1, ENDF/B-VII and JENDL-4.0 evaluated nuclear data libraries, except for the inelastic contributions around $E_{n} = 10-13$ MeV. All three libraries significantly underestimate the inelastic contributions. The inelastic contributions are further studied, using the Talys simulation code and the experimental spectra are reproduced reasonably well in the whole energy range by the Talys calculation, including the inelastic contributions.

R. Han; R. Wada; Z. Chen; Y. Nie; X. Liu; S. Zhang; P. Ren; B. Jia; G. Tian; F. Luo; W. Lin; J. Liu; F. Shi; M. Huang; X. Ruan; J. Ren; Z. Zhou; H. Huang; J. Bao; K. Zhang; B. Hu

2014-11-03

438

Osteomyelitis and infarction in sickle cell hemoglobinopathies: differentiation by combined technetium and gallium scintigraphy  

SciTech Connect

Clinical records and scintigrams were reviewed of 18 patients with sickle cell hemoglobinophaties who had undergone combined technetium and gallium scintigraphy during 22 separate episodes of suspected osseous infection. The combined scintigrams were correctly interpreted as indicating osteomyelitis in four studies. Of 18 studies in patients with infarction, the combined scintigrams were correctly interpreted in 16 and showed either no local accumulation of Ga-67 or less accumulation than that of Tc-99m MDP at symptomatic sites. In the other two studies, the scintigrams were falsely interpreted as indicating osteomyelitis and showed congruent, increased accumulation of both Tc-99, MDP and Ga-67. This pattern must be considered indeterminate. Overall, the results indicate that the combination of technetium and gallium scintigraphy is an effective means to distinguish osteomyelitis from infarction in patients with sickle cell hemoglobinopathies.

Amundsen, T.R.; Siegel, M.J.; Siegel, B.A.

1984-12-01

439

Electrodeposition of Ga-O Thin Films from Aqueous Gallium Sulfate Solutions  

NASA Astrophysics Data System (ADS)

Ga-O based thin films were electrodeposited on fluorine-doped tin oxide (FTO)-coated glass substrate at room temperature from aqueous gallium sulfate solution with hydrogen peroxide (H2O2). Effects of different deposition parameters such as deposition voltage, amount of H2O2 and deposition time were investigated and presented. Nearly smooth and crack-free morphologies were attained at -1.0 V vs SCE deposition potential. As-deposited films showed O to Ga ratio of 2.0, which signified GaOOH formation. Thermal annealing of the as-deposited films in ambient air at 500-600 °C reduced the O/Ga ratio closer to stoichiometric gallium oxide (Ga2O3) and retained the morphology of Ga-O thin films. As-prepared films with ˜0.2 µm thickness had 80% transparency in the visible wavelength range.

Vequizo, Junie Jhon M.; Ichimura, Masaya

2013-07-01

440

The Baksan Neutrino Observatory Soviet-American Gallium Solar Neutrino Experiment  

SciTech Connect

A radiochemical /sup 71/Ga-/sup 71/Ge experiment to determine the integral flux of neutrinos from the sun is currently under preparation at the Baksan Neutrino Observatory in the USSR. Measurements are scheduled to commence by late 1988 with 30 tonnes of metallic gallium. A fractional statistical accuracy of 18% is expected to be obtained after one year of operation if the solar signal obtained after one year of operation if the solar signal is 70 SNU, the flux expected from p-p neutrinos alone. While initial measurements are in progress, 30 additional tonnes of gallium will be installed in order to perform the full experiment with a 60-tonne target. 28 refs.

Abazov, A.I.; Abdurashitov, D.N.; Anosov, O.V.; Avdeyev, A.V.; Belouska, Yu. I.; Bychuk, O.V.; Danshin, S.N.; Eroshkina, L.A.; Faizov, E.L.; Gavrin, V.N.

1988-01-01

441

Wideband tunable microwave devices using ferromagnetic film-gallium arsenide material structures  

NASA Astrophysics Data System (ADS)

Yittrium iron garnet (YIG)-gadolinium gallium garnet (GGG) and iron (Fe)-gallium arsenide (GaAs) layer structures have been used, respectively, to construct wideband tunable microwave bandstop filters of the flip-chip type and the integrated type. For the former, a frequency tuning range of 2.5-23.0 GHz was accomplished at a magnetic field tuning range of 290-7300 Oe. For the latter, a comparable tuning bandwidth but of significantly higher carrier frequencies of 10.7-32.5 GHz has been achieved at a much lower magnetic field tuning range, namely, 0-4500 Oe. The advantages associated with the Fe-film-based bandstop filters should also accompany other analog microwave devices.

Tsai, Chen S.

2000-01-01

442

Distinctive Signature of Indium Gallium Nitride Quantum Dot Lasing in Microdisks Cavities  

E-print Network

Low threshold lasers realized within compact, high quality optical cavities enable a variety of nanophotonics applications. Gallium nitride (GaN) materials containing indium gallium nitride (InGaN) quantum dots and quantum wells offer an outstanding platform to study light matter interactions and realize practical devices such as efficient light emitting diodes and nanolasers. Despite progress in the growth and characterization of InGaN quantum dots, their advantages as the gain medium in low threshold lasers have not been clearly demonstrated. This work seeks to better understand the reasons for these limitations by focusing on the simpler, limited-mode microdisk cavities, and by carrying out comparisons of lasing dynamics in those cavities using varying gain media including InGaN quantum wells, fragmented quantum wells, and a combination of fragmented quantum wells with quantum dots. For each gain medium, we utilize the distinctive, high quality (Q~5500) modes of the cavities, and the change in the highest ...

Woolf, Alexander; Aharanovich, Igor; Zhu, Tongtong; Niu, Nan; Wang, Danqing; Oliver, Rachel A; Hu, Evelyn L

2014-01-01

443

Implications of Gallium Solar Neutrino Data for the Resonant Spin-Flavor Precession Scenario  

E-print Network

We consider the implications of the recent results of SAGE and GALLEX experiments for the solution of the solar neutrino problem in the framework of the resonant neutrino spin-flavor precession scenario. It is shown that this scenario is consistent with all the existing solar neutrino data including the gallium results. The quality of the fit of the data depends crucially on the magnetic field profile used which makes it possible to get information about the magnetic field in the solar interior. In particular, the magnetic field in the core of the sun must not be too strong ($<3 \\times 10^6$ G). The detection rate in the gallium detectors turns out to be especially sensitive to the magnitude of $\\Delta m^2$. Predictions for forthcoming solar-neutrino experiments are made.

E. Kh. Akhmedov; A. Lanza; S. T. Petcov

1993-01-14

444

In vitro corrosion behavior and microstructure examination of a gallium-based restorative.  

PubMed

Concerns of mercury toxicity have led to the development of gallium-based restorative materials to replace dental amalgam. A new gallium-based dental restorative, Galloy, was compared with a high-copper amalgam, Permite, for anodic polarization behavior in deoxygenated Ringer's solution and by immersion testing in normal Ringer's solution at 37 degrees C. Corrosion products were analyzed using energy dispersive X-ray spectrometry and transmission electron diffraction. The data from both sources were consistent with the presence of alpha-Ga2O3 and SnO2 as the primary corrosion products of Galloy. Anodic polarization behavior of Galloy- and Permite-coupled specimens suggests that coupling Galloy with the more noble Permite amalgam may cause accelerated electrochemical corrosion and that Galloy is more corrosion prone than Permite. PMID:9484143

DeSchepper, E J; Oshida, Y; Moore, B K; Cook, N B; Eggertson, H

1997-01-01

445

Growth of epitaxial iron nitride ultrathin film on zinc-blende gallium nitride  

SciTech Connect

The authors report the growth of iron nitride on zinc-blende gallium nitride using molecular beam epitaxy. First, zinc-blende GaN is grown on a magnesium oxide substrate having (001) orientation; second, an ultrathin layer of FeN is grown on top of the GaN layer. In situ reflection high-energy electron diffraction is used to monitor the surface during growth, and a well-defined epitaxial relationship is observed. Cross-sectional transmission electron microscopy is used to reveal the epitaxial continuity at the gallium nitride-iron nitride interface. Surface morphology of the iron nitride, similar to yet different from that of the GaN substrate, can be described as plateau valley. The FeN chemical stoichiometry is probed using both bulk and surface sensitive methods, and the magnetic properties of the sample are revealed.

Pak, J.; Lin, W.; Wang, K.; Chinchore, A.; Shi, M.; Ingram, D. C.; Smith, A. R.; Sun, K.; Lucy, J. M.; Hauser, A. J.; Yang, F. Y. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Department of Physics, The Ohio State University, 191 Woodruff Avenue, Columbus, Ohio 43210 (United States)

2010-07-15

446

High temperature oxidation of plutonium-1 wt % gallium in 94. 5% nitrogen\\/5. 5% oxygen atmospheres  

Microsoft Academic Search

The oxidation of plutonium-1 wt % gallium in 500 torr of a mixture of 94.5% nitrogen\\/5.5% oxygen has been investigated over the temperature range of 150 to 500°C. This atmosphere typifies the atmospheres in the Rocky Flats inert glovebox lines. Rates of oxidation were nearly identical to the rates measured in an air atmosphere. The mechanism for the oxidation were

J. L. Stakebake; L. A. Lewis

1986-01-01

447

The optical and electrical effects of high concentrations of defects in irradiated crystalline gallium arsenide  

Microsoft Academic Search

The damage produced by fast neutron irradiation of gallium arsenide has been studied by a number of techniques. The electrical resistivity, which increases with dose at low doses to semi-insulating values, shows a remarkable, specimen-independent decrease for doses greater than 1017 n cm-2 from values of ca. 109 Omega cm to 3 Omega cm for the highest dose of 1.5

R. Coates; E. W. J. Mitchell

1975-01-01

448

Surface Passivation for 3-5 Semiconductor Processing: Stable Gallium Sulphide Films by MOCVD  

NASA Technical Reports Server (NTRS)

Gallium sulphide (GaS) has been deposited on GaAs to form stable, insulating, passivating layers. Spectrally resolved photoluminescence and surface recombination velocity measurements indicate that the GaS itself can contribute a significant fraction of the photoluminescence in GaS/GaAs structures. Determination of surface recombination velocity by photoluminescence is therefore difficult. By using C-V analysis of metal-insulator-semiconductor structures, passivation of the GaAs with GaS films is quantified.

Macinnes, Andrew N.; Jenkins, Phillip P.; Power, Michael B.; Kang, Soon; Barron, Andrew R.; Hepp, Aloysius F.; Tabib-Azar, Massood

1994-01-01

449

Removal and recovery of gallium ion from solution by insoluble amphoteric starches  

Microsoft Academic Search

The removal and recovery of gallium ion (Ga[sup +3]) from a solution with the high cross-linked amphoteric starches containing the phosphate anionic group and the quaternary ammonium or tertiary amine cationic group was investigated. The adsorption capacity of tertiary amine phosphate starch (TAP) and quaternary ammonium phosphate starch (QAP) is 0.54 and 0.48 meq\\/g, respectively. The adsorption process has been

Wu-Chung Chan; Wuchung

1993-01-01

450

Strain sensitivity in the nitrogen 1s NEXAFS spectra of gallium nitride  

NASA Astrophysics Data System (ADS)

The nitrogen 1s near edge X-ray absorption fine structure (NEXAFS) of gallium nitride (GaN) shows a strong natural linear dichroism that arises from its anisotropic wurtzite structure. An additional spectroscopic variation arises from lattice strain in epitaxially grown GaN thin films. This variation is directly proportional to the degree of strain for some spectroscopic features. This strain variation is interpreted with the aid of density functional theory calculations.

Ritchie, Andrew; Eger, Shaylin; Wright, Chelsey; Chelladurai, Daniel; Borrowman, Cuyler; Olovsson, Weine; Magnuson, Martin; Verma, Jai; Jena, Debdeep; Xing, Huili Grace; Dubuc, Christian; Urquhart, Stephen

2014-10-01

451

Ferromagnetic resonance of single-crystal YIG\\/gadolinium gallium garnet\\/YIG layers  

Microsoft Academic Search

We report on the microwave properties of single-crystal YIG\\/gadolinium gallium garnet\\/YIG grown in (110) layers, where YIG is yttrium iron garnet. The YIG layers were sufficiently thin so that single domain ferromagnetic resonance (FMR) was observed. FMR fields were measured as a function of field direction and magnitude and frequency. Bulk magnetic parameters deduced from FMR and vibrating-sample magnetometer measurements

Kunquan Sun; Carmine Vittoria; H. L. Glass; P. de Gasperis; R. Marcelli

1990-01-01

452

Forward-biased current annealing of radiation degraded indium phosphide and gallium arsenide solar cells  

Microsoft Academic Search

The preliminary results of a novel approach to low-temperature annealing of previously irradiated indium phosphide and gallium arsenide solar cells are reported. The technique is based on forward-biased current annealing. The two types of III-V solar cells were irradiated with 1-MeV electrons to a fluence level of (1-10) x 10 to the 14th electrons\\/sq cm. Several annealing attempts were made,

Sherif Michael; Corinne Cypranowski; Bruce Anspaugh

1990-01-01

453

Power recovery of radiation-damaged Gallium Arsenide and Indium Phosphide solar cells  

Microsoft Academic Search

Radiation damaging to on-orbit solar arrays was found to significantly decrease power output and efficiency. By a process of annealing, these cells can recover some of the initial performance parameters. Gallium Arsenide (GaAs) and Indium Phosphide (InP) solar cells were subjected to 1 MeV electron radiation by a Dynamitron linear accelerator at two fluence levels of 1E14 and 1E15 electrons\\/sq

Corinne Cypranowski

1989-01-01

454

Power recovery of radiation-damaged gallium arsenide and indium phosphide solar cells. Master's thesis  

Microsoft Academic Search

Radiation damaging to on-orbit solar arrays was found to significantly decrease power output and efficiency. By a process of annealing, these cells can recover some of the initial performance parameters. Gallium Arsenide (GaAs) and Indium Phosphide (InP) solar cells were subjected to 1 MeV electron radiation by a Dynamitron linear accelerator at two fluence levels of 1E14 and 1E15 electrons\\/sq

Cypranowski

1989-01-01

455

New developments in gallium doped zinc oxide deposited on polymeric substrates by RF magnetron sputtering  

Microsoft Academic Search

Gallium-doped zinc oxide (GZO) thin films have been deposited onto polyethylene naphthalate (PEN) substrates by r.f. magnetron sputtering at room temperature. The influence of the film thickness (from 70 to 890 nm) on the electrical, structural and morphological properties are presented. The lowest resistivity obtained was 5×10?4 ? cm with a Hall mobility of 13.7 cm2\\/Vs and a carrier concentration

E. Fortunato; A. Gonçalves; A. Marques; A. Viana; H. Águas; L. Pereira; I. Ferreira; P. Vilarinho; R. Martins

2004-01-01

456

Influence of fast neutrons on the recombination and electrical properties of neutron transmutation doped gallium arsenide  

SciTech Connect

The electrical properties, photoluminescence and DLTS spectra of LEC gallium arsenide crystals after neutron transmutation doping (NTD) has been investigated as function of starting material properties, irradiation dose and thermal to fast neutron fluences-ratio. The residual carbon acceptors interact with radiation induced defects (RD) in neutron irradiated GaAs crystals and formed nonradiative recombination centers, which are stable up to 700 C temperature.

Bykovsky, V.A.; Karas, V.I.; Shoh, V.F. [Research Inst. of Radiomaterials, Minsk (Belarus); Strzelecka, S.; Hruban, A.; Gladysz, M. [Inst. of Electronic Materials Technology, Warsaw (Poland)

1996-12-31

457

An advanced space photovoltaic concentrator array using Fresnel lenses, gallium arsenide cells, and prismatic cell covers  

NASA Technical Reports Server (NTRS)

The current status of a space concentrator array which uses refractive optics, gallium arsenide cells, and prismatic cell covers to achieve excellent performance at a very low array mass is documented. The prismatically covered cells have established records for space cell performance (24.2 percent efficient at 100 AM0 suns and 25 C) and terrestrial single-junction cell performance (29.3 percent efficient at 200 AM1.5 suns and 25 C).

O'Neill, Mark J.; Piszczor, Michael F.

1988-01-01

458

Plastic deformation of piezoelectric lanthanum-gallium tantalate crystals during cyclic mechanical actions  

NASA Astrophysics Data System (ADS)

The microstructure of piezoelectric lanthanum-gallium tantalite single crystals is shown to change substantially during cyclic mechanical actions at room temperature and during thermal shock: the dislocation density increases, twinning takes place, and a mesostructure forms. This effect is related to the appearance of piezoelectric fields, which significantly decrease the temperature of the onset of plastic deformation of these brittle single crystals, during mechanical actions.

Kugaenko, O. M.; Uvarova, S. S.; Petrakov, V. S.; Buzanov, O. A.; Egorov, V. N.; Sakharov, S. A.; Pozdnyakov, M. L.

2013-04-01

459

Electronic Raman Spectra: Crystal Field in Terbium Aluminum Garnet and Europium Gallium Garnet  

Microsoft Academic Search

The crystal-field splittings of the 7F multiplet of Eu3+ and Tb3+ have been determined in europium gallium garnet (EuGaG) and terbium aluminum garnet (TbAlG) from light scattering, fluorescence, and absorption spectra. The data were used to derive a set of crystal-field parameters for the two garnet systems. In these calculations the Hamiltonian appropriate for the D2 symmetry of the rare-earth

D. Boal; P. Grunberg; J. A. Koningstein

1973-01-01

460

Self-focusing in Terbium Gallium Garnet using Z-scan  

NASA Astrophysics Data System (ADS)

When illuminated near its resonance with an Ar ion laser beam ( ?=488 nm), laser induced thermal self-focusing is observed in Terbium Gallium Garnet. The crystal exhibits a strong intensity dependent refractive index change ? n. The Z-scan technique is used to study the beam waist change due to ? n. The refractive index is found to be well described by a quadratic spatial distribution model. Both the sign and the distribution coefficient of ? n are determined.

Chen, X.; Lavorel, B.; Dreier, T.; Genetier, N.; Misserey, H.; Michaut, X.

461

Self-focusing in Terbium Gallium Garnet using Z-scan  

Microsoft Academic Search

When illuminated near its resonance with an Ar ion laser beam (lambda=488 nm), laser induced thermal self-focusing is observed in Terbium Gallium Garnet. The crystal exhibits a strong intensity dependent refractive index change Deltan. The Z-scan technique is used to study the beam waist change due to Deltan. The refractive index is found to be well described by a quadratic

Chen Lavorel; Dreier Genetier; Misserey Michaut

1998-01-01

462

Self-focusing in Terbium Gallium Garnet using Z-scan  

NASA Astrophysics Data System (ADS)

When illuminated near its resonance with an Ar ion laser beam (?=488 nm), laser induced thermal self-focusing is observed in Terbium Gallium Garnet. The crystal exhibits a strong intensity dependent refractive index change ?n. The Z-scan technique is used to study the beam waist change due to ?n. The refractive index is found to be well described by a quadratic spatial distribution model. Both the sign and the distribution coefficient of ?n are determined.

Lavorel, Chen; Genetier, Dreier; Michaut, Misserey

1998-08-01

463

Electronic Raman scattering from terbium gallium garnet excited with a picosecond laser  

NASA Astrophysics Data System (ADS)

The electronic Raman (ER) spectrum of terbium gallium garnet, recorded using picosecond radiation from the frequency-doubled output of a Nd:YAG laser is reported. The observed spectral bands with frequency shifts up to 6000 cm-1 are the result of the effect of a strong crystal field which causes J-mixing between the 7F 6,5,....,0 states. The site symmetry of Tb 3+ in the garnet can be confirmed from this spectroscopy.

Koningstein, J. A.; Lemaire, H.; Atkinson, G. H.

1987-09-01

464

A study of a strongly geometrically frustrated magnet: Gadolinium gallium garnet  

Microsoft Academic Search

Geometrically frustrated antiferromagnets are materials in which the geometry of the lattice results in frustration of the antiferromagnetic (AFM) exchange interactions. They are characterized by the absence of long-range order at temperatures well below the Curie-Weiss temperature (theta cw). One such material is Gd3Ga5O12 (gadolinium gallium garnet or GGG), in which the magnetic Gd ions are on three-dimensional (3D) corner-sharing

Yee-Kin Tsui

2000-01-01

465

Optical properties of some sol–gel-derived gallium-doped ZnO films  

Microsoft Academic Search

Gallium-doped zinc oxide (ZnO) films with different concentrations have been prepared by sol–gel technique. The films are optically transparent and electrically conducting. The optical transmission and reflection data for the films have been analyzed. The optical absorption coefficient (?) and hence the refractive index (n), extinction coefficient (k) and the band gap (Eg) have been determined for these films using

G. K Paul; S. K Sen

2002-01-01

466

Erbium, chromium:yttrium–scandium–gallium–garnet laser-assisted sinus graft procedure  

Microsoft Academic Search

The possibility of using lasers in the field of dentistry has been a subject of investigation. There are few reports that\\u000a any laser systems have been used for bony window osteotomy by direct sinus grafting. In this study, erbium, chromium:yttrium–scandium–gallium–garnet\\u000a (Er,Cr:YSGG) laser of various laser systems was used for 12 sinus bone grafts in ten patients, and the efficiency of

Dong-Seok Sohn; Ji-Soo Lee; Kyung-Mi An; George E. Romanos

2009-01-01

467

Contribution of gallium experiments to the understanding of solar physics and neutrino physics  

SciTech Connect

The results of gallium measurements of solar neutrino and measurements with artificial sources of neutrinos are presented. Conclusions are drawn from these results, and the potential of the SAGE experiment for studying transitions of active neutrinos to sterile states for {Delta}m{sup 2} > 0.5 eV{sup 2} and a sensitivity of a few percent to the disappearance of electron neutrinos is examined.

Gavrin, V. N., E-mail: gavrin@inr.ru [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)

2013-10-15

468

Evaluation of mineral content of dentin prepared by erbium, chromium:yttrium scandium gallium garnet laser  

Microsoft Academic Search

Laser etching has an effect on the mineral content of dentin. The aim of this study was to evaluate the mineral content of\\u000a dentin prepared at three different power settings with an erbium, chromium:yttrium scandium gallium garnet (Er,Cr:YSGG) laser.\\u000a The enamel of five, lower, wisdom, molar teeth was removed to expose the dentin surface. Four dentin slabs were obtained,\\u000a then

Asli Secilmis; Subutayhan Altintas; Aslihan Usumez; Gizem Berk

2008-01-01

469

High-resistivity and conductive gallium arsenide for IR optical components  

Microsoft Academic Search

Infrared (IR) windows and domes for use with electro-optic (EO) systems operating in the 8- to 12-micrometer region are currently fabricated from the following limited number of materials: germanium (Ge), zinc sulfide (ZnS), and a zinc selenide (ZnSe) sandwich. A multiyear development effort at T